diff --git a/src/main.cc b/src/main.cc
index 43b9675a..3cdbf997 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -59,27 +59,27 @@ void register_env_vars()
 {
     static const struct {
         const char* name;
-        String (*func)(const String&, const Context&);
+        String (*func)(StringView, const Context&);
     } env_vars[] = { {
             "bufname",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { return context.buffer().display_name(); }
         }, {
             "buffile",
-            [](const String& name, const Context& context) -> String
+            [](StringView name, const Context& context) -> String
             { return context.buffer().name(); }
         }, {
             "timestamp",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { return to_string(context.buffer().timestamp()); }
         }, {
             "selection",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { const Selection& sel = context.selections().main();
               return content(context.buffer(), sel); }
         }, {
             "selections",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { auto sels = context.selections_content();
               String res;
               for (size_t i = 0; i < sels.size(); ++i)
@@ -91,55 +91,55 @@ void register_env_vars()
               return res; }
         }, {
             "runtime",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { return runtime_directory(); }
         }, {
             "opt_.+",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { return context.options()[name.substr(4_byte)].get_as_string(); }
         }, {
             "reg_.+",
-            [](const String& name, const Context& context) -> String
+            [](StringView name, const Context& context) -> String
             { return RegisterManager::instance()[name[4]].values(context)[0]; }
         }, {
             "client_env_.+",
-            [](const String& name, const Context& context) -> String
+            [](StringView name, const Context& context) -> String
             { return context.client().get_env_var(name.substr(11_byte)); }
         }, {
             "session",
-            [](const String& name, const Context& context) -> String
+            [](StringView name, const Context& context) -> String
             { return Server::instance().session(); }
         }, {
             "client",
-            [](const String& name, const Context& context) -> String
+            [](StringView name, const Context& context) -> String
             { return context.name(); }
         }, {
             "cursor_line",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { return to_string(context.selections().main().cursor().line + 1); }
         }, {
             "cursor_column",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { return to_string(context.selections().main().cursor().column + 1); }
         }, {
             "cursor_char_column",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { auto coord = context.selections().main().cursor();
               return to_string(context.buffer()[coord.line].char_count_to(coord.column) + 1); }
         }, {
             "selection_desc",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { auto& sel = context.selections().main();
                 auto beg = sel.min();
                 return to_string(beg.line + 1) + ':' + to_string(beg.column + 1) + '+' +
                        to_string((int)context.buffer().distance(beg, sel.max())+1); }
         }, {
             "window_width",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { return to_string(context.window().dimensions().column); }
         }, {
             "window_height",
-            [](const String& name, const Context& context)
+            [](StringView name, const Context& context)
             { return to_string(context.window().dimensions().line); }
     } };
 
diff --git a/src/shell_manager.cc b/src/shell_manager.cc
index bdda6c05..448b3ddc 100644
--- a/src/shell_manager.cc
+++ b/src/shell_manager.cc
@@ -16,15 +16,15 @@ ShellManager::ShellManager()
 {
 }
 
-String ShellManager::eval(const String& cmdline, const Context& context,
+String ShellManager::eval(StringView cmdline, const Context& context,
                           memoryview<String> params,
                           const EnvVarMap& env_vars)
 {
     return pipe("", cmdline, context, params, env_vars);
 }
 
-String ShellManager::pipe(const String& input,
-                          const String& cmdline, const Context& context,
+String ShellManager::pipe(StringView input,
+                          StringView cmdline, const Context& context,
                           memoryview<String> params,
                           const EnvVarMap& env_vars)
 {
@@ -43,8 +43,7 @@ String ShellManager::pipe(const String& input,
         close(read_pipe[1]);
         close(error_pipe[1]);
 
-        auto data = input.data();
-        write(write_pipe[1], data.pointer(), data.size());
+        write(write_pipe[1], input.data(), (int)input.length());
         close(write_pipe[1]);
 
         char buffer[1024];
@@ -79,18 +78,18 @@ String ShellManager::pipe(const String& input,
         dup2(error_pipe[1], 2); close(error_pipe[1]);
         dup2(write_pipe[0], 0); close(write_pipe[0]);
 
-        boost::regex_iterator<String::const_iterator> it(cmdline.begin(), cmdline.end(), env_var_regex);
-        boost::regex_iterator<String::const_iterator> end;
+        boost::regex_iterator<StringView::iterator> it(cmdline.begin(), cmdline.end(), env_var_regex);
+        boost::regex_iterator<StringView::iterator> end;
 
         while (it != end)
         {
             auto& match = *it;
 
-            String name;
+            StringView name;
             if (match[1].matched)
-                name = String(match[1].first, match[1].second);
+                name = StringView(match[1].first, match[1].second);
             else if (match[2].matched)
-                name = String(match[2].first, match[2].second);
+                name = StringView(match[2].first, match[2].second);
             else
                 kak_assert(false);
             kak_assert(name.length() > 0);
@@ -111,7 +110,7 @@ String ShellManager::pipe(const String& input,
                     try
                     {
                         String value = env_var->second(name, context);
-                        setenv(("kak_" + name).c_str(), value.c_str(), 1);
+                        setenv(("kak_"_str + name).c_str(), value.c_str(), 1);
                     }
                     catch (runtime_error&) {}
                 }
@@ -119,22 +118,23 @@ String ShellManager::pipe(const String& input,
 
             ++it;
         }
-        String shell = "/bin/sh";
-        std::vector<const char*> execparams = { shell.c_str(), "-c", cmdline.c_str() };
+        const char* shell = "/bin/sh";
+        auto cmdlinezstr = cmdline.zstr();
+        std::vector<const char*> execparams = { shell, "-c", cmdlinezstr };
         if (not params.empty())
-            execparams.push_back(shell.c_str());
+            execparams.push_back(shell);
         for (auto& param : params)
             execparams.push_back(param.c_str());
         execparams.push_back(nullptr);
 
-        execvp(shell.c_str(), (char* const*)execparams.data());
+        execvp(shell, (char* const*)execparams.data());
         exit(-1);
     }
     catch (...) { exit(-1); }
     return output;
 }
 
-void ShellManager::register_env_var(const String& regex,
+void ShellManager::register_env_var(StringView regex,
                                     EnvVarRetriever retriever)
 {
     m_env_vars.push_back({ Regex(regex.begin(), regex.end()), std::move(retriever) });
diff --git a/src/shell_manager.hh b/src/shell_manager.hh
index a6fe38fd..742ba1cd 100644
--- a/src/shell_manager.hh
+++ b/src/shell_manager.hh
@@ -9,23 +9,23 @@ namespace Kakoune
 {
 
 class Context;
-using EnvVarRetriever = std::function<String (const String& name, const Context&)>;
+using EnvVarRetriever = std::function<String (StringView name, const Context&)>;
 
 class ShellManager : public Singleton<ShellManager>
 {
 public:
     ShellManager();
 
-    String eval(const String& cmdline, const Context& context,
+    String eval(StringView cmdline, const Context& context,
                 memoryview<String> params,
                 const EnvVarMap& env_vars);
 
-    String pipe(const String& input,
-                const String& cmdline, const Context& context,
+    String pipe(StringView input,
+                StringView cmdline, const Context& context,
                 memoryview<String> params,
                 const EnvVarMap& env_vars);
 
-    void register_env_var(const String& regex, EnvVarRetriever retriever);
+    void register_env_var(StringView regex, EnvVarRetriever retriever);
 
 private:
     std::vector<std::pair<Regex, EnvVarRetriever>> m_env_vars;