diff --git a/src/command_manager.cc b/src/command_manager.cc
index 1f199fd0..2255b7c4 100644
--- a/src/command_manager.cc
+++ b/src/command_manager.cc
@@ -23,7 +23,7 @@ void CommandManager::register_command(String command_name,
     m_commands[command_name] = { std::move(command), std::move(completer) };
 }
 
-void CommandManager::register_commands(const memoryview<String>& command_names,
+void CommandManager::register_commands(memoryview<String> command_names,
                                        Command command,
                                        CommandCompleter completer)
 {
@@ -247,7 +247,7 @@ struct command_not_found : runtime_error
         : runtime_error(command + " : no such command") {}
 };
 
-void CommandManager::execute_single_command(const CommandParameters& params,
+void CommandManager::execute_single_command(CommandParameters params,
                                             Context& context) const
 {
     if (params.empty())
@@ -262,7 +262,7 @@ void CommandManager::execute_single_command(const CommandParameters& params,
 
 void CommandManager::execute(const String& command_line,
                              Context& context,
-                             const memoryview<String>& shell_params,
+                             memoryview<String> shell_params,
                              const EnvVarMap& env_vars)
 {
     TokenList tokens = parse(command_line);
@@ -368,7 +368,7 @@ Completions CommandManager::complete(const Context& context,
 }
 
 CandidateList PerArgumentCommandCompleter::operator()(const Context& context,
-                                                      const CommandParameters& params,
+                                                      CommandParameters params,
                                                       size_t token_to_complete,
                                                       ByteCount pos_in_token) const
 {
diff --git a/src/command_manager.hh b/src/command_manager.hh
index 2c272f03..c63633ef 100644
--- a/src/command_manager.hh
+++ b/src/command_manager.hh
@@ -21,10 +21,10 @@ struct parse_error : runtime_error
 
 struct Context;
 using CommandParameters = memoryview<String>;
-using Command = std::function<void (const CommandParameters&,
+using Command = std::function<void (CommandParameters,
                                     Context& context)>;
 using CommandCompleter = std::function<CandidateList (const Context& context,
-                                                      const CommandParameters&,
+                                                      CommandParameters,
                                                       size_t, ByteCount)>;
 
 class PerArgumentCommandCompleter
@@ -34,11 +34,11 @@ public:
                                             const String&, ByteCount)>;
     using ArgumentCompleterList = memoryview<ArgumentCompleter>;
 
-    PerArgumentCommandCompleter(const ArgumentCompleterList& completers)
+    PerArgumentCommandCompleter(ArgumentCompleterList completers)
         : m_completers(completers.begin(), completers.end()) {}
 
     CandidateList operator()(const Context& context,
-                             const CommandParameters& params,
+                             CommandParameters params,
                              size_t token_to_complete,
                              ByteCount pos_in_token) const;
 
@@ -50,7 +50,7 @@ class CommandManager : public Singleton<CommandManager>
 {
 public:
     void execute(const String& command_line, Context& context,
-                 const memoryview<String>& shell_params = {},
+                 memoryview<String> shell_params = {},
                  const EnvVarMap& env_vars = EnvVarMap{});
 
     Completions complete(const Context& context,
@@ -62,12 +62,12 @@ public:
                           Command command,
                           CommandCompleter completer = CommandCompleter());
 
-    void register_commands(const memoryview<String>& command_names,
+    void register_commands(memoryview<String> command_names,
                            Command command,
                            CommandCompleter completer = CommandCompleter());
 
 private:
-    void execute_single_command(const CommandParameters& params,
+    void execute_single_command(CommandParameters params,
                                 Context& context) const;
     struct CommandDescriptor
     {
diff --git a/src/commands.cc b/src/commands.cc
index 82d0cbc3..0b27d278 100644
--- a/src/commands.cc
+++ b/src/commands.cc
@@ -86,7 +86,7 @@ Buffer* open_fifo(const String& name , const String& filename, Context& context)
 }
 
 template<bool force_reload>
-void edit(const CommandParameters& params, Context& context)
+void edit(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "scratch", false },
                                       { "fifo", true } },
@@ -134,7 +134,7 @@ void edit(const CommandParameters& params, Context& context)
     }
 }
 
-void write_buffer(const CommandParameters& params, Context& context)
+void write_buffer(CommandParameters params, Context& context)
 {
     if (params.size() > 1)
         throw wrong_argument_count();
@@ -153,7 +153,7 @@ void write_buffer(const CommandParameters& params, Context& context)
         buffer.notify_saved();
 }
 
-void write_all_buffers(const CommandParameters& params, Context& context)
+void write_all_buffers(CommandParameters params, Context& context)
 {
     if (params.size() != 0)
         throw wrong_argument_count();
@@ -169,7 +169,7 @@ void write_all_buffers(const CommandParameters& params, Context& context)
 }
 
 template<bool force>
-void quit(const CommandParameters& params, Context& context)
+void quit(CommandParameters params, Context& context)
 {
     if (params.size() != 0)
         throw wrong_argument_count();
@@ -200,13 +200,13 @@ void quit(const CommandParameters& params, Context& context)
 }
 
 template<bool force>
-void write_and_quit(const CommandParameters& params, Context& context)
+void write_and_quit(CommandParameters params, Context& context)
 {
     write_buffer(params, context);
     quit<force>(CommandParameters(), context);
 }
 
-void show_buffer(const CommandParameters& params, Context& context)
+void show_buffer(CommandParameters params, Context& context)
 {
     if (params.size() != 1)
         throw wrong_argument_count();
@@ -223,7 +223,7 @@ void show_buffer(const CommandParameters& params, Context& context)
 }
 
 template<bool force>
-void delete_buffer(const CommandParameters& params, Context& context)
+void delete_buffer(CommandParameters params, Context& context)
 {
     if (params.size() > 1)
         throw wrong_argument_count();
@@ -239,7 +239,7 @@ void delete_buffer(const CommandParameters& params, Context& context)
     manager.delete_buffer(buffer);
 }
 
-void set_buffer_name(const CommandParameters& params, Context& context)
+void set_buffer_name(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, OptionMap{},
                             ParametersParser::Flags::None, 1, 1);
@@ -258,7 +258,7 @@ Group& get_group(Group& root, const String& group_path)
         return group;
 }
 
-void add_highlighter(const CommandParameters& params, Context& context)
+void add_highlighter(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "group", true } }, ParametersParser::Flags::None, 1);
     HighlighterRegistry& registry = HighlighterRegistry::instance();
@@ -278,7 +278,7 @@ void add_highlighter(const CommandParameters& params, Context& context)
     group.append(factory(highlighter_params, window));
 }
 
-void rm_highlighter(const CommandParameters& params, Context& context)
+void rm_highlighter(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "group", true } }, ParametersParser::Flags::None, 1, 1);
 
@@ -290,7 +290,7 @@ void rm_highlighter(const CommandParameters& params, Context& context)
     group.remove(parser[0]);
 }
 
-void add_filter(const CommandParameters& params, Context& context)
+void add_filter(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "group", true } }, ParametersParser::Flags::None, 1);
 
@@ -311,7 +311,7 @@ void add_filter(const CommandParameters& params, Context& context)
     group.append(factory(filter_params));
 }
 
-void rm_filter(const CommandParameters& params, Context& context)
+void rm_filter(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "group", true } }, ParametersParser::Flags::None, 1, 1);
 
@@ -334,7 +334,7 @@ static HookManager& get_hook_manager(const String& scope, Context& context)
     throw runtime_error("error: no such hook container " + scope);
 }
 
-void add_hook(const CommandParameters& params, Context& context)
+void add_hook(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "id", true } }, ParametersParser::Flags::None, 4, 4);
     // copy so that the lambda gets a copy as well
@@ -349,13 +349,13 @@ void add_hook(const CommandParameters& params, Context& context)
     get_hook_manager(parser[0], context).add_hook(parser[1], id, hook_func);
 }
 
-void rm_hooks(const CommandParameters& params, Context& context)
+void rm_hooks(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, {}, ParametersParser::Flags::None, 2, 2);
     get_hook_manager(parser[0], context).remove_hooks(parser[1]);
 }
 
-EnvVarMap params_to_env_var_map(const CommandParameters& params)
+EnvVarMap params_to_env_var_map(CommandParameters params)
 {
     std::unordered_map<String, String> vars;
     char param_name[] = "param0";
@@ -367,7 +367,7 @@ EnvVarMap params_to_env_var_map(const CommandParameters& params)
     return vars;
 }
 
-void define_command(const CommandParameters& params, Context& context)
+void define_command(CommandParameters params, Context& context)
 {
     ParametersParser parser(params,
                             { { "env-params", false },
@@ -389,20 +389,20 @@ void define_command(const CommandParameters& params, Context& context)
     Command cmd;
     if (parser.has_option("env-params"))
     {
-        cmd = [=](const CommandParameters& params, Context& context) {
+        cmd = [=](CommandParameters params, Context& context) {
             CommandManager::instance().execute(commands, context, {},
                                                params_to_env_var_map(params));
         };
     }
     if (parser.has_option("shell-params"))
     {
-        cmd = [=](const CommandParameters& params, Context& context) {
+        cmd = [=](CommandParameters params, Context& context) {
             CommandManager::instance().execute(commands, context, params);
         };
     }
     else
     {
-        cmd = [=](const CommandParameters& params, Context& context) {
+        cmd = [=](CommandParameters params, Context& context) {
             if (not params.empty())
                 throw wrong_argument_count();
             CommandManager::instance().execute(commands, context);
@@ -412,7 +412,7 @@ void define_command(const CommandParameters& params, Context& context)
     CommandCompleter completer;
     if (parser.has_option("file-completion"))
     {
-        completer = [](const Context& context, const CommandParameters& params,
+        completer = [](const Context& context, CommandParameters params,
                        size_t token_to_complete, ByteCount pos_in_token)
         {
              const String& prefix = token_to_complete < params.size() ?
@@ -423,7 +423,7 @@ void define_command(const CommandParameters& params, Context& context)
     else if (parser.has_option("shell-completion"))
     {
         String shell_cmd = parser.option_value("shell-completion");
-        completer = [=](const Context& context, const CommandParameters& params,
+        completer = [=](const Context& context, CommandParameters params,
                         size_t token_to_complete, ByteCount pos_in_token)
         {
             EnvVarMap vars = {
@@ -437,7 +437,7 @@ void define_command(const CommandParameters& params, Context& context)
     CommandManager::instance().register_command(cmd_name, cmd, completer);
 }
 
-void echo_message(const CommandParameters& params, Context& context)
+void echo_message(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "color", true } },
                             ParametersParser::Flags::OptionsOnlyAtStart);
@@ -449,7 +449,7 @@ void echo_message(const CommandParameters& params, Context& context)
     context.print_status({ std::move(message), color } );
 }
 
-void write_debug_message(const CommandParameters& params, Context&)
+void write_debug_message(CommandParameters params, Context&)
 {
     String message;
     for (auto& param : params)
@@ -457,7 +457,7 @@ void write_debug_message(const CommandParameters& params, Context&)
     write_debug(message);
 }
 
-void exec_commands_in_file(const CommandParameters& params,
+void exec_commands_in_file(CommandParameters params,
                            Context& context)
 {
     if (params.size() != 1)
@@ -467,7 +467,7 @@ void exec_commands_in_file(const CommandParameters& params,
     CommandManager::instance().execute(file_content, context);
 }
 
-void set_global_option(const CommandParameters& params, Context& context)
+void set_global_option(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "add", false } },
                             ParametersParser::Flags::OptionsOnlyAtStart,
@@ -480,7 +480,7 @@ void set_global_option(const CommandParameters& params, Context& context)
         opt.set_from_string(parser[1]);
 }
 
-void set_buffer_option(const CommandParameters& params, Context& context)
+void set_buffer_option(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "buffer", true}, { "add", false } },
                             ParametersParser::Flags::OptionsOnlyAtStart,
@@ -497,7 +497,7 @@ void set_buffer_option(const CommandParameters& params, Context& context)
         opt.set_from_string(parser[1]);
 }
 
-void set_window_option(const CommandParameters& params, Context& context)
+void set_window_option(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "add", false } },
                             ParametersParser::Flags::OptionsOnlyAtStart,
@@ -510,7 +510,7 @@ void set_window_option(const CommandParameters& params, Context& context)
         opt.set_from_string(parser[1]);
 }
 
-void declare_option(const CommandParameters& params, Context& context)
+void declare_option(CommandParameters params, Context& context)
 {
     if (params.size() != 2 and params.size() != 3)
         throw wrong_argument_count();
@@ -538,7 +538,7 @@ void declare_option(const CommandParameters& params, Context& context)
 }
 
 template<typename Func>
-void context_wrap(const CommandParameters& params, Context& context, Func func)
+void context_wrap(CommandParameters params, Context& context, Func func)
 {
     ParametersParser parser(params, { { "client", true }, { "draft", false }},
                             ParametersParser::Flags::OptionsOnlyAtStart, 1);
@@ -562,7 +562,7 @@ void context_wrap(const CommandParameters& params, Context& context, Func func)
         real_context.window().forget_timestamp();
 }
 
-void exec_string(const CommandParameters& params, Context& context)
+void exec_string(CommandParameters params, Context& context)
 {
     context_wrap(params, context, [](const ParametersParser& parser, Context& context) {
         KeyList keys;
@@ -575,7 +575,7 @@ void exec_string(const CommandParameters& params, Context& context)
     });
 }
 
-void eval_string(const CommandParameters& params, Context& context)
+void eval_string(CommandParameters params, Context& context)
 {
     context_wrap(params, context, [](const ParametersParser& parser, Context& context) {
         String command;
@@ -585,7 +585,7 @@ void eval_string(const CommandParameters& params, Context& context)
     });
 }
 
-void menu(const CommandParameters& params, Context& context)
+void menu(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "auto-single", false },
                                       { "select-cmds", false } });
@@ -694,7 +694,7 @@ static String assist(String message, CharCount maxWidth)
 }
 
 
-void info(const CommandParameters& params, Context& context)
+void info(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, { { "anchor", true }, { "assist", false } },
                             ParametersParser::Flags::None, 0, 1);
@@ -724,7 +724,7 @@ void info(const CommandParameters& params, Context& context)
     }
 }
 
-void try_catch(const CommandParameters& params, Context& context)
+void try_catch(CommandParameters params, Context& context)
 {
     if (params.size() != 3)
         throw wrong_argument_count();
@@ -742,7 +742,7 @@ void try_catch(const CommandParameters& params, Context& context)
     }
 }
 
-void define_color_alias(const CommandParameters& params, Context& context)
+void define_color_alias(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, OptionMap{},
                             ParametersParser::Flags::None, 2, 2);
@@ -750,7 +750,7 @@ void define_color_alias(const CommandParameters& params, Context& context)
         parser[0], parser[1], true);
 }
 
-void set_client_name(const CommandParameters& params, Context& context)
+void set_client_name(CommandParameters params, Context& context)
 {
     ParametersParser parser(params, OptionMap{},
                             ParametersParser::Flags::None, 1, 1);
@@ -758,7 +758,7 @@ void set_client_name(const CommandParameters& params, Context& context)
     manager.set_client_name(manager.get_client(context), params[0]);
 }
 
-void set_register(const CommandParameters& params, Context& context)
+void set_register(CommandParameters params, Context& context)
 {
     if (params.size() != 2)
         throw wrong_argument_count();
@@ -768,7 +768,7 @@ void set_register(const CommandParameters& params, Context& context)
     RegisterManager::instance()[params[0][0]] = memoryview<String>(params[1]);
 }
 
-void change_working_directory(const CommandParameters& params, Context&)
+void change_working_directory(CommandParameters params, Context&)
 {
     if (params.size() != 1)
         throw wrong_argument_count();
@@ -780,7 +780,7 @@ void change_working_directory(const CommandParameters& params, Context&)
 template<typename GetRootGroup>
 CommandCompleter group_rm_completer(GetRootGroup get_root_group)
 {
-    return [=](const Context& context, const CommandParameters& params,
+    return [=](const Context& context, CommandParameters params,
                size_t token_to_complete, ByteCount pos_in_token) {
         auto& root_group = get_root_group(context);
         const String& arg = token_to_complete < params.size() ?
@@ -796,7 +796,7 @@ CommandCompleter group_rm_completer(GetRootGroup get_root_group)
 template<typename FactoryRegistry, typename GetRootGroup>
 CommandCompleter group_add_completer(GetRootGroup get_root_group)
 {
-    return [=](const Context& context, const CommandParameters& params,
+    return [=](const Context& context, CommandParameters params,
                size_t token_to_complete, ByteCount pos_in_token) {
         auto& root_group = get_root_group(context);
         const String& arg = token_to_complete < params.size() ?
@@ -842,7 +842,7 @@ public:
 
     void print_status(const DisplayLine&) override {}
     void draw(const DisplayBuffer&, const DisplayLine&) override {}
-    void menu_show(const memoryview<String>&,
+    void menu_show(memoryview<String>,
                    DisplayCoord, ColorPair, ColorPair, MenuStyle) override {}
     void menu_select(int) override {}
     void menu_hide() override {}
@@ -887,7 +887,7 @@ void register_commands()
 {
     CommandManager& cm = CommandManager::instance();
 
-    cm.register_commands({"nop"}, [](const CommandParameters&, Context&){});
+    cm.register_commands({"nop"}, [](CommandParameters, Context&){});
 
     PerArgumentCommandCompleter filename_completer({
          [](const Context& context, const String& prefix, ByteCount cursor_pos)
diff --git a/src/editor.cc b/src/editor.cc
index eed0fbe2..c03fd396 100644
--- a/src/editor.cc
+++ b/src/editor.cc
@@ -93,7 +93,7 @@ void Editor::insert(const String& str, InsertMode mode)
     check_invariant();
 }
 
-void Editor::insert(const memoryview<String>& strings, InsertMode mode)
+void Editor::insert(memoryview<String> strings, InsertMode mode)
 {
     scoped_edition edition(*this);
     if (strings.empty())
@@ -542,7 +542,7 @@ void IncrementalInserter::insert(String content)
     }
 }
 
-void IncrementalInserter::insert(const memoryview<String>& strings)
+void IncrementalInserter::insert(memoryview<String> strings)
 {
     auto& buffer = m_editor.buffer();
     for (size_t i = 0; i < m_editor.m_selections.size(); ++i)
diff --git a/src/editor.hh b/src/editor.hh
index bf70af70..0104d43d 100644
--- a/src/editor.hh
+++ b/src/editor.hh
@@ -50,7 +50,7 @@ public:
 
     void insert(const String& string,
                 InsertMode mode = InsertMode::Insert);
-    void insert(const memoryview<String>& strings,
+    void insert(memoryview<String> strings,
                 InsertMode mode = InsertMode::Insert);
 
     void move_selections(LineCount move,
@@ -126,7 +126,7 @@ public:
     ~IncrementalInserter();
 
     void insert(String content);
-    void insert(const memoryview<String>& strings);
+    void insert(memoryview<String> strings);
     void erase();
     void move_cursors(CharCount move);
     void move_cursors(LineCount move);
diff --git a/src/file.cc b/src/file.cc
index c2cd645c..ed4a8276 100644
--- a/src/file.cc
+++ b/src/file.cc
@@ -184,7 +184,7 @@ Buffer* create_buffer_from_file(String filename)
     return buffer;
 }
 
-static void write(int fd, const memoryview<char>& data, const String& filename)
+static void write(int fd, memoryview<char> data, const String& filename)
 {
     const char* ptr = data.pointer();
     ssize_t count   = data.size();
@@ -228,7 +228,7 @@ void write_buffer_to_file(const Buffer& buffer, const String& filename)
     }
 }
 
-String find_file(const String& filename, const memoryview<String>& paths)
+String find_file(const String& filename, memoryview<String> paths)
 {
     for (auto candidate : paths)
     {
diff --git a/src/file.hh b/src/file.hh
index a8422d0d..4a93117f 100644
--- a/src/file.hh
+++ b/src/file.hh
@@ -31,7 +31,7 @@ String compact_path(const String& filename);
 String read_file(const String& filename);
 Buffer* create_buffer_from_file(String filename);
 void write_buffer_to_file(const Buffer& buffer, const String& filename);
-String find_file(const String& filename, const memoryview<String>& paths);
+String find_file(const String& filename, memoryview<String> paths);
 
 std::vector<String> complete_filename(const String& prefix,
                                       const Regex& ignore_regex,
diff --git a/src/filter.hh b/src/filter.hh
index a33ea5c2..b863efeb 100644
--- a/src/filter.hh
+++ b/src/filter.hh
@@ -24,7 +24,7 @@ using FilterAndId = std::pair<String, FilterFunc>;
 using FilterGroup = FunctionGroup<Buffer&, Selection&, String&>;
 
 using FilterParameters = memoryview<String>;
-using FilterFactory = std::function<FilterAndId (const FilterParameters& params)>;
+using FilterFactory = std::function<FilterAndId (FilterParameters params)>;
 
 struct FilterRegistry : FunctionRegistry<FilterFactory>,
                         Singleton<FilterRegistry>
diff --git a/src/filters.cc b/src/filters.cc
index 02be6767..34d5d8b5 100644
--- a/src/filters.cc
+++ b/src/filters.cc
@@ -99,7 +99,7 @@ private:
     String m_replacement;
 };
 
-FilterAndId regex_filter_factory(const FilterParameters& params)
+FilterAndId regex_filter_factory(FilterParameters params)
 {
     if (params.size() != 3)
         throw runtime_error("wrong parameter count");
@@ -114,7 +114,7 @@ class SimpleFilterFactory
 public:
     SimpleFilterFactory(const String& id) : m_id(id) {}
 
-    FilterAndId operator()(const FilterParameters& params) const
+    FilterAndId operator()(FilterParameters params) const
     {
         return FilterAndId(m_id, FilterFunc(filter_func));
     }
@@ -122,7 +122,7 @@ private:
     String m_id;
 };
 
-FilterAndId filter_group_factory(const FilterParameters& params)
+FilterAndId filter_group_factory(FilterParameters params)
 {
     if (params.size() != 1)
         throw runtime_error("wrong parameter count");
diff --git a/src/highlighter.hh b/src/highlighter.hh
index dba7fe11..e3561bee 100644
--- a/src/highlighter.hh
+++ b/src/highlighter.hh
@@ -24,7 +24,7 @@ typedef std::function<void (const Window& window, DisplayBuffer& display_buffer)
 typedef std::pair<String, HighlighterFunc> HighlighterAndId;
 typedef memoryview<String> HighlighterParameters;
 
-using HighlighterFactory = std::function<HighlighterAndId (const HighlighterParameters& params,
+using HighlighterFactory = std::function<HighlighterAndId (HighlighterParameters params,
                                                            Window& window)>;
 
 using HighlighterGroup = FunctionGroup<const Window&, DisplayBuffer&>;
diff --git a/src/highlighters.cc b/src/highlighters.cc
index 940d4025..f0f54631 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -117,7 +117,7 @@ private:
     }
 };
 
-HighlighterAndId colorize_regex_factory(const HighlighterParameters params, const Window&)
+HighlighterAndId colorize_regex_factory(HighlighterParameters params, const Window&)
 {
     if (params.size() < 2)
         throw runtime_error("wrong parameter count");
@@ -179,7 +179,7 @@ private:
     RegexGetter    m_regex_getter;
 };
 
-HighlighterAndId highlight_search_factory(const HighlighterParameters params, const Window&)
+HighlighterAndId highlight_search_factory(HighlighterParameters params, const Window&)
 {
     if (params.size() != 1)
         throw runtime_error("wrong parameter count");
@@ -198,7 +198,7 @@ HighlighterAndId highlight_search_factory(const HighlighterParameters params, co
     }
 }
 
-HighlighterAndId highlight_regex_option_factory(const HighlighterParameters params, const Window& window)
+HighlighterAndId highlight_regex_option_factory(HighlighterParameters params, const Window& window)
 {
     if (params.size() != 2)
         throw runtime_error("wrong parameter count");
@@ -446,7 +446,7 @@ private:
 };
 std::unordered_map<const Option*, std::weak_ptr<FlagLines::OptionUpdater>> FlagLines::ms_updaters;
 
-HighlighterAndId flag_lines_factory(const HighlighterParameters& params, Window& window)
+HighlighterAndId flag_lines_factory(HighlighterParameters params, Window& window)
 {
     if (params.size() != 2)
         throw runtime_error("wrong parameter count");
@@ -460,7 +460,7 @@ class SimpleHighlighterFactory
 public:
     SimpleHighlighterFactory(const String& id) : m_id(id) {}
 
-    HighlighterAndId operator()(const HighlighterParameters& params, const Window&) const
+    HighlighterAndId operator()(HighlighterParameters params, const Window&) const
     {
         return HighlighterAndId(m_id, HighlighterFunc(highlighter_func));
     }
@@ -468,7 +468,7 @@ private:
     String m_id;
 };
 
-HighlighterAndId highlighter_group_factory(const HighlighterParameters& params, const Window&)
+HighlighterAndId highlighter_group_factory(HighlighterParameters params, const Window&)
 {
     if (params.size() != 1)
         throw runtime_error("wrong parameter count");
diff --git a/src/input_handler.cc b/src/input_handler.cc
index 997c6e96..5d6f437a 100644
--- a/src/input_handler.cc
+++ b/src/input_handler.cc
@@ -161,7 +161,7 @@ private:
 class Menu : public InputMode
 {
 public:
-    Menu(InputHandler& input_handler, const memoryview<String>& choices,
+    Menu(InputHandler& input_handler, memoryview<String> choices,
          MenuCallback callback)
         : InputMode(input_handler),
           m_callback(callback), m_choices(choices.begin(), choices.end()),
@@ -269,7 +269,7 @@ private:
     LineEditor   m_filter_editor;
 };
 
-String common_prefix(const memoryview<String>& strings)
+String common_prefix(memoryview<String> strings)
 {
     String res;
     if (strings.empty())
@@ -879,7 +879,7 @@ void InputHandler::set_prompt_colors(ColorPair prompt_colors)
         prompt->set_prompt_colors(prompt_colors);
 }
 
-void InputHandler::menu(const memoryview<String>& choices,
+void InputHandler::menu(memoryview<String> choices,
                         MenuCallback callback)
 {
     m_mode_trash.emplace_back(std::move(m_mode));
diff --git a/src/input_handler.hh b/src/input_handler.hh
index 5dccced1..ccd8426c 100644
--- a/src/input_handler.hh
+++ b/src/input_handler.hh
@@ -57,7 +57,7 @@ public:
     // abort or validation with corresponding MenuEvent value
     // returns to normal mode after validation if callback does
     // not change the mode itself
-    void menu(const memoryview<String>& choices,
+    void menu(memoryview<String> choices,
               MenuCallback callback);
 
     // execute callback on next keypress and returns to normal mode
diff --git a/src/ncurses.cc b/src/ncurses.cc
index 80c3dcb0..f5fcb973 100644
--- a/src/ncurses.cc
+++ b/src/ncurses.cc
@@ -413,7 +413,7 @@ void NCursesUI::draw_menu()
     redraw();
 }
 
-void NCursesUI::menu_show(const memoryview<String>& choices,
+void NCursesUI::menu_show(memoryview<String> choices,
                           DisplayCoord anchor, ColorPair fg, ColorPair bg,
                           MenuStyle style)
 {
diff --git a/src/ncurses.hh b/src/ncurses.hh
index 497bbb5e..2cdcd06d 100644
--- a/src/ncurses.hh
+++ b/src/ncurses.hh
@@ -26,7 +26,7 @@ public:
     bool   is_key_available() override;
     Key    get_key() override;
 
-    void menu_show(const memoryview<String>& choices,
+    void menu_show(memoryview<String> choices,
                    DisplayCoord anchor, ColorPair fg, ColorPair bg,
                    MenuStyle style) override;
     void menu_select(int selected) override;
diff --git a/src/option_types.hh b/src/option_types.hh
index 9c07a6c1..7156af69 100644
--- a/src/option_types.hh
+++ b/src/option_types.hh
@@ -109,7 +109,7 @@ struct TupleOptionDetail
                tuple_separator + escape(option_to_string(std::get<I>(opt)), tuple_separator, '\\');
     }
 
-    static void from_string(const memoryview<String>& elems, std::tuple<Types...>& opt)
+    static void from_string(memoryview<String> elems, std::tuple<Types...>& opt)
     {
         option_from_string(elems[I], std::get<I>(opt));
         TupleOptionDetail<I-1, Types...>::from_string(elems, opt);
@@ -124,7 +124,7 @@ struct TupleOptionDetail<0, Types...>
         return option_to_string(std::get<0>(opt));
     }
 
-    static void from_string(const memoryview<String>& elems, std::tuple<Types...>& opt)
+    static void from_string(memoryview<String> elems, std::tuple<Types...>& opt)
     {
         option_from_string(elems[0], std::get<0>(opt));
     }
diff --git a/src/register.hh b/src/register.hh
index 96781b36..74e34365 100644
--- a/src/register.hh
+++ b/src/register.hh
@@ -13,7 +13,7 @@ class Register
 {
 public:
     virtual ~Register() {}
-    virtual Register& operator=(const memoryview<String>& values) = 0;
+    virtual Register& operator=(memoryview<String> values) = 0;
 
     virtual memoryview<String> values(const Context& context) = 0;
 };
diff --git a/src/register_manager.cc b/src/register_manager.cc
index 88f706b8..0fb17141 100644
--- a/src/register_manager.cc
+++ b/src/register_manager.cc
@@ -11,7 +11,7 @@ namespace Kakoune
 class StaticRegister : public Register
 {
 public:
-    Register& operator=(const memoryview<String>& values) override
+    Register& operator=(memoryview<String> values) override
     {
         m_content = std::vector<String>(values.begin(), values.end());
         return *this;
@@ -40,7 +40,7 @@ public:
     DynamicRegister(RegisterRetriever function)
         : m_function(std::move(function)) {}
 
-    Register& operator=(const memoryview<String>& values) override
+    Register& operator=(memoryview<String> values) override
     {
         throw runtime_error("this register is not assignable");
     }
diff --git a/src/remote.cc b/src/remote.cc
index 5fe996d6..3e0f8a56 100644
--- a/src/remote.cc
+++ b/src/remote.cc
@@ -62,7 +62,7 @@ public:
     };
 
     template<typename T>
-    void write(const memoryview<T>& view)
+    void write(memoryview<T> view)
     {
         write<uint32_t>(view.size());
         for (auto& val : view)
@@ -213,7 +213,7 @@ public:
 
     void print_status(const DisplayLine& status) override;
 
-    void menu_show(const memoryview<String>& choices,
+    void menu_show(memoryview<String> choices,
                    DisplayCoord anchor, ColorPair fg, ColorPair bg,
                    MenuStyle style) override;
     void menu_select(int selected) override;
@@ -258,7 +258,7 @@ void RemoteUI::print_status(const DisplayLine& status)
     msg.write(status);
 }
 
-void RemoteUI::menu_show(const memoryview<String>& choices,
+void RemoteUI::menu_show(memoryview<String> choices,
                          DisplayCoord anchor, ColorPair fg, ColorPair bg,
                          MenuStyle style)
 {
diff --git a/src/shell_manager.cc b/src/shell_manager.cc
index dcb5afd8..d293a137 100644
--- a/src/shell_manager.cc
+++ b/src/shell_manager.cc
@@ -17,7 +17,7 @@ ShellManager::ShellManager()
 }
 
 String ShellManager::eval(const String& cmdline, const Context& context,
-                          const memoryview<String>& params,
+                          memoryview<String> params,
                           const EnvVarMap& env_vars)
 {
     return pipe("", cmdline, context, params, env_vars);
@@ -25,7 +25,7 @@ String ShellManager::eval(const String& cmdline, const Context& context,
 
 String ShellManager::pipe(const String& input,
                           const String& cmdline, const Context& context,
-                          const memoryview<String>& params,
+                          memoryview<String> params,
                           const EnvVarMap& env_vars)
 {
     int write_pipe[2]; // child stdin
diff --git a/src/shell_manager.hh b/src/shell_manager.hh
index fce3e0af..6748b609 100644
--- a/src/shell_manager.hh
+++ b/src/shell_manager.hh
@@ -19,12 +19,12 @@ public:
     ShellManager();
 
     String eval(const String& cmdline, const Context& context,
-                const memoryview<String>& params,
+                memoryview<String> params,
                 const EnvVarMap& env_vars);
 
     String pipe(const String& input,
                 const String& cmdline, const Context& context,
-                const memoryview<String>& params,
+                memoryview<String> params,
                 const EnvVarMap& env_vars);
 
     void register_env_var(const String& regex, EnvVarRetriever retriever);
diff --git a/src/user_interface.hh b/src/user_interface.hh
index c80d72b0..2e2b6171 100644
--- a/src/user_interface.hh
+++ b/src/user_interface.hh
@@ -28,7 +28,7 @@ public:
     virtual ~UserInterface() {}
     virtual void print_status(const DisplayLine& status) = 0;
 
-    virtual void menu_show(const memoryview<String>& choices,
+    virtual void menu_show(memoryview<String> choices,
                            DisplayCoord anchor, ColorPair fg, ColorPair bg,
                            MenuStyle style) = 0;
     virtual void menu_select(int selected) = 0;