diff --git a/src/buffer.cc b/src/buffer.cc
index aa6314d6..3c402905 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -273,31 +273,28 @@ ByteCoord Buffer::do_insert(ByteCoord pos, StringView content)
     }
     else
     {
-        String prefix = m_lines[pos.line].substr(0, pos.column);
-        String suffix = m_lines[pos.line].substr(pos.column);
+        StringView prefix = m_lines[pos.line].substr(0, pos.column);
+        StringView suffix = m_lines[pos.line].substr(pos.column);
 
-        std::vector<String> new_lines;
+        std::vector<InternedString> new_lines;
 
         ByteCount start = 0;
         for (ByteCount i = 0; i < content.length(); ++i)
         {
             if (content[i] == '\n')
             {
-                String line_content = content.substr(start, i + 1 - start);
+                StringView line_content = content.substr(start, i + 1 - start);
                 if (start == 0)
-                {
-                    line_content = prefix + line_content;
-                    new_lines.push_back(std::move(line_content));
-                }
+                    new_lines.emplace_back(prefix + line_content);
                 else
-                    new_lines.push_back(std::move(line_content));
+                    new_lines.push_back(line_content);
                 start = i + 1;
             }
         }
         if (start == 0)
-            new_lines.push_back(prefix + content + suffix);
+            new_lines.emplace_back(prefix + content + suffix);
         else if (start != content.length() or not suffix.empty())
-            new_lines.push_back(content.substr(start) + suffix);
+            new_lines.emplace_back(content.substr(start) + suffix);
 
         LineCount last_line = pos.line + new_lines.size() - 1;
 
@@ -327,7 +324,7 @@ ByteCoord Buffer::do_erase(ByteCoord begin, ByteCoord end)
     if (new_line.length() != 0)
     {
         m_lines.erase(m_lines.begin() + (int)begin.line, m_lines.begin() + (int)end.line);
-        m_lines[begin.line] = std::move(new_line);
+        m_lines[begin.line] = InternedString(new_line);
         next = begin;
     }
     else
@@ -368,21 +365,24 @@ void Buffer::apply_modification(const Modification& modification)
     }
 }
 
-BufferIterator Buffer::insert(const BufferIterator& pos, String content)
+BufferIterator Buffer::insert(const BufferIterator& pos, StringView content)
 {
     kak_assert(is_valid(pos.coord()));
     if (content.empty())
         return pos;
 
+    InternedString real_content;
     if (pos == end() and content.back() != '\n')
-        content += '\n';
+        real_content = InternedString(content + "\n");
+    else
+        real_content = content;
 
     // for undo and redo purpose it is better to use one past last line rather
     // than one past last char coord.
     auto coord = pos == end() ? ByteCoord{line_count()} : pos.coord();
     if (not (m_flags & Flags::NoUndo))
-        m_current_undo_group.emplace_back(Modification::Insert, coord, content);
-    return {*this, do_insert(pos.coord(), content)};
+        m_current_undo_group.emplace_back(Modification::Insert, coord, real_content);
+    return {*this, do_insert(pos.coord(), real_content)};
 }
 
 BufferIterator Buffer::erase(BufferIterator begin, BufferIterator end)
@@ -396,7 +396,7 @@ BufferIterator Buffer::erase(BufferIterator begin, BufferIterator end)
 
     if (not (m_flags & Flags::NoUndo))
         m_current_undo_group.emplace_back(Modification::Erase, begin.coord(),
-                                          string(begin.coord(), end.coord()));
+                                          InternedString(string(begin.coord(), end.coord())));
     return {*this, do_erase(begin.coord(), end.coord())};
 }
 
@@ -452,7 +452,7 @@ ByteCoord Buffer::char_next(ByteCoord coord) const
 {
     if (coord.column < m_lines[coord.line].length() - 1)
     {
-        auto& line = m_lines[coord.line];
+        auto line = m_lines[coord.line];
         coord.column += utf8::codepoint_size(line[(int)coord.column]);
         // Handle invalid utf-8
         if (coord.column >= line.length())
@@ -483,7 +483,7 @@ ByteCoord Buffer::char_prev(ByteCoord coord) const
     }
     else
     {
-        auto& line = m_lines[coord.line];
+        auto line = m_lines[coord.line];
         coord.column = (int)(utf8::character_start(line.begin() + (int)coord.column - 1, line.begin()) - line.begin());
     }
     return coord;
diff --git a/src/buffer.hh b/src/buffer.hh
index e24bc786..01504170 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -6,7 +6,7 @@
 #include "option_manager.hh"
 #include "keymap_manager.hh"
 #include "safe_ptr.hh"
-#include "string.hh"
+#include "interned_string.hh"
 #include "value.hh"
 
 #include <vector>
@@ -92,7 +92,7 @@ public:
 
     bool set_name(String name);
 
-    BufferIterator insert(const BufferIterator& pos, String content);
+    BufferIterator insert(const BufferIterator& pos, StringView content);
     BufferIterator erase(BufferIterator begin, BufferIterator end);
 
     size_t         timestamp() const;
@@ -126,7 +126,7 @@ public:
     BufferIterator end() const;
     LineCount      line_count() const;
 
-    const String&  operator[](LineCount line) const
+    const StringView& operator[](LineCount line) const
     { return m_lines[line]; }
 
     // returns an iterator at given coordinates. clamp line_and_column
@@ -178,15 +178,15 @@ private:
 
     void on_option_changed(const Option& option) override;
 
-    struct LineList : std::vector<String>
+    struct LineList : std::vector<InternedString>
     {
         [[gnu::always_inline]]
-        String& operator[](LineCount line)
-        { return std::vector<String>::operator[]((int)line); }
+        InternedString& operator[](LineCount line)
+        { return std::vector<InternedString>::operator[]((int)line); }
 
         [[gnu::always_inline]]
-        const String& operator[](LineCount line) const
-        { return std::vector<String>::operator[]((int)line); }
+        const InternedString& operator[](LineCount line) const
+        { return std::vector<InternedString>::operator[]((int)line); }
     };
     LineList m_lines;
 
diff --git a/src/buffer_utils.cc b/src/buffer_utils.cc
index 19e35552..eadf6415 100644
--- a/src/buffer_utils.cc
+++ b/src/buffer_utils.cc
@@ -11,7 +11,7 @@ namespace Kakoune
 CharCount get_column(const Buffer& buffer,
                      CharCount tabstop, ByteCoord coord)
 {
-    auto& line = buffer[coord.line];
+    auto line = buffer[coord.line];
     auto col = 0_char;
     for (auto it = line.begin();
          it != line.end() and coord.column > (int)(it - line.begin());
diff --git a/src/display_buffer.hh b/src/display_buffer.hh
index e8451753..8ad01661 100644
--- a/src/display_buffer.hh
+++ b/src/display_buffer.hh
@@ -31,7 +31,7 @@ public:
         {
             case BufferRange:
             {
-                auto& line = (*m_buffer)[m_begin.line];
+                auto line = (*m_buffer)[m_begin.line];
                 if (m_begin.line == m_end.line)
                     return line.substr(m_begin.column, m_end.column - m_begin.column);
                 else if (m_begin.line+1 == m_end.line and m_end.column == 0)
diff --git a/src/highlighters.cc b/src/highlighters.cc
index 310ab223..a42b6c94 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -724,8 +724,8 @@ void find_matches(const Buffer& buffer, RegexMatchList& matches, const Regex& re
     const size_t buf_timestamp = buffer.timestamp();
     for (auto line = 0_line, end = buffer.line_count(); line < end; ++line)
     {
-        auto& l = buffer[line];
-        for (boost::regex_iterator<String::const_iterator> it{l.begin(), l.end(), regex}, end{}; it != end; ++it)
+        auto l = buffer[line];
+        for (boost::regex_iterator<const char*> it{l.begin(), l.end(), regex}, end{}; it != end; ++it)
         {
             ByteCount b = (int)((*it)[0].first - l.begin());
             ByteCount e = (int)((*it)[0].second - l.begin());
@@ -778,8 +778,8 @@ void update_matches(const Buffer& buffer, memoryview<LineModification> modifs,
              line < modif.new_line + modif.num_added+1 and
              line < buffer.line_count(); ++line)
         {
-            auto& l = buffer[line];
-            for (boost::regex_iterator<String::const_iterator> it{l.begin(), l.end(), regex}, end{}; it != end; ++it)
+            auto l = buffer[line];
+            for (boost::regex_iterator<const char*> it{l.begin(), l.end(), regex}, end{}; it != end; ++it)
             {
                 ByteCount b = (int)((*it)[0].first - l.begin());
                 ByteCount e = (int)((*it)[0].second - l.begin());
diff --git a/src/interned_string.hh b/src/interned_string.hh
index 5d81afd3..23984a5d 100644
--- a/src/interned_string.hh
+++ b/src/interned_string.hh
@@ -39,7 +39,7 @@ public:
 
     InternedString(const char* str) : StringView() { acquire_ifn(str); }
     InternedString(StringView str) : StringView() { acquire_ifn(str); }
-    InternedString(const String& str) : StringView() { acquire_ifn(str); }
+    //InternedString(const String& str) : StringView() { acquire_ifn(str); }
 
     InternedString& operator=(const InternedString& str)
     {
diff --git a/src/normal.cc b/src/normal.cc
index 9b6ea48e..fbd23ae8 100644
--- a/src/normal.cc
+++ b/src/normal.cc
@@ -804,7 +804,7 @@ void deindent(Context& context, int)
         for (auto line = sel.min().line; line < sel.max().line+1; ++line)
         {
             CharCount width = 0;
-            auto& content = buffer[line];
+            auto content = buffer[line];
             for (auto column = 0_byte; column < content.length(); ++column)
             {
                 const char c = content[column];
@@ -1105,7 +1105,7 @@ void copy_indent(Context& context, int selection)
         selection = context.selections().main_index() + 1;
 
     auto ref_line = selections[selection-1].min().line;
-    const String& line = buffer[ref_line];
+    auto line = buffer[ref_line];
     auto it = line.begin();
     while (it != line.end() and is_horizontal_blank(*it))
         ++it;
@@ -1117,7 +1117,7 @@ void copy_indent(Context& context, int selection)
         if (l == ref_line)
             continue;
 
-        auto& line = buffer[l];
+        auto line = buffer[l];
         ByteCount i = 0;
         while (i < line.length() and is_horizontal_blank(line[i]))
             ++i;
diff --git a/src/remote.cc b/src/remote.cc
index a5643387..12bdf580 100644
--- a/src/remote.cc
+++ b/src/remote.cc
@@ -35,7 +35,7 @@ class Message
 {
 public:
     Message(int sock) : m_socket(sock) {}
-    ~Message()
+    ~Message() noexcept(false)
     {
         if (m_stream.size() == 0)
             return;
diff --git a/src/selection.cc b/src/selection.cc
index f4640e5e..b188a2fe 100644
--- a/src/selection.cc
+++ b/src/selection.cc
@@ -410,8 +410,8 @@ namespace
 
 inline void _avoid_eol(const Buffer& buffer, ByteCoord& coord)
 {
-    const auto column = coord.column;
-    const auto& line = buffer[coord.line];
+    auto column = coord.column;
+    auto line = buffer[coord.line];
     if (column != 0 and column == line.length() - 1)
         coord.column = line.byte_count_to(line.char_length() - 2);
 }