diff --git a/src/common/DebugHelpers.cpp b/src/common/DebugHelpers.cpp
index 1683070350d..1dd49668e24 100644
--- a/src/common/DebugHelpers.cpp
+++ b/src/common/DebugHelpers.cpp
@@ -80,7 +80,7 @@ void Surge::Debug::stackTraceToStdout(int depth)
 }
 
 static std::atomic<int> lcdepth(0);
-Surge::Debug::LifeCycleToConsole::LifeCycleToConsole(std::string st) : s(st)
+Surge::Debug::LifeCycleToConsole::LifeCycleToConsole(const std::string &st) : s(st)
 {
     lcdepth++;
     for (int i = 0; i < lcdepth; ++i)
diff --git a/src/common/DebugHelpers.h b/src/common/DebugHelpers.h
index fbcabcadd19..7aca7824820 100644
--- a/src/common/DebugHelpers.h
+++ b/src/common/DebugHelpers.h
@@ -30,7 +30,7 @@ void stackTraceToStdout(int depth = -1); // no-op on Windows; shows stack trace
 
 struct LifeCycleToConsole
 { // simple class which printfs in ctor and dtor
-    LifeCycleToConsole(std::string s);
+    LifeCycleToConsole(const std::string &s);
     ~LifeCycleToConsole();
     std::string s;
 };
diff --git a/src/common/FilterConfiguration.h b/src/common/FilterConfiguration.h
index b764bbc38fb..52cb423ea72 100644
--- a/src/common/FilterConfiguration.h
+++ b/src/common/FilterConfiguration.h
@@ -325,7 +325,7 @@ struct FilterSelectorMapper : public ParameterDiscreteIndexRemapper
 {
     std::vector<std::pair<int, std::string>> mapping;
     std::unordered_map<int, int> inverseMapping;
-    void p(int i, std::string s) { mapping.push_back(std::make_pair(i, s)); }
+    void p(int i, const std::string &s) { mapping.push_back(std::make_pair(i, s)); }
     FilterSelectorMapper()
     {
         p(fut_none, "");
@@ -475,7 +475,7 @@ struct WaveShaperSelectorMapper : public ParameterDiscreteIndexRemapper
 {
     std::vector<std::pair<int, std::string>> mapping;
     std::unordered_map<int, int> inverseMapping;
-    void p(int i, std::string s) { mapping.emplace_back(i, s); }
+    void p(int i, const std::string &s) { mapping.emplace_back(i, s); }
     WaveShaperSelectorMapper()
     {
         // Obviously improve this
diff --git a/src/common/Parameter.cpp b/src/common/Parameter.cpp
index 1efe30115dd..a2ff0d93c87 100644
--- a/src/common/Parameter.cpp
+++ b/src/common/Parameter.cpp
@@ -3758,9 +3758,12 @@ bool Parameter::can_setvalue_from_string()
     return false;
 }
 
-bool Parameter::set_value_from_string(std::string s) { return set_value_from_string_onto(s, val); }
+bool Parameter::set_value_from_string(const std::string &s)
+{
+    return set_value_from_string_onto(s, val);
+}
 
-bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
+bool Parameter::set_value_from_string_onto(const std::string &s, pdata &ontoThis)
 {
     const char *c = s.c_str();
 
@@ -3811,13 +3814,14 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
                 int neg = 1;
 
                 // convert string to lowercase
-                std::for_each(s.begin(), s.end(),
+                auto lowerS = s;
+                std::for_each(lowerS.begin(), lowerS.end(),
                               [](char &c) { c = ::tolower(static_cast<unsigned char>(c)); });
 
                 // find the unmodified note
                 for (int i = 0; i < 7; i++)
                 {
-                    n = s.find(notes[i]);
+                    n = lowerS.find(notes[i]);
                     if (n != std::string::npos)
                     {
                         val = pitches[i];
@@ -3827,31 +3831,32 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
 
                 // check if the following character is sharp or flat, adjust val if so
                 n++;
-                if ((m = s.find("#", n, 1)) != std::string::npos)
+                if ((m = lowerS.find("#", n, 1)) != std::string::npos)
                 {
                     val += 1;
                     n++;
                 }
-                else if ((m = s.find("b", n, 1)) != std::string::npos)
+                else if ((m = lowerS.find("b", n, 1)) != std::string::npos)
                 {
                     val -= 1;
                     n++;
                 }
 
                 // if neither note modifiers are found, check for minus
-                if ((m = s.find("-", n, 1)) != std::string::npos)
+                if ((m = lowerS.find("-", n, 1)) != std::string::npos)
                 {
                     neg = -1;
                     n++;
                 }
 
                 // finally, octave number
-                s = s.substr(n, s.length() - n); // trim the fat to the left of current char
+                auto q = lowerS.substr(n, lowerS.length() -
+                                              n); // trim the fat to the left of current char
 
                 int oct;
                 try
                 {
-                    oct = std::stoi(s);
+                    oct = std::stoi(q);
                 }
                 catch (std::invalid_argument const &)
                 {
@@ -3873,7 +3878,7 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
 
         if (ni >= val_min.i && ni <= val_max.i)
         {
-            onto.i = ni;
+            ontoThis.i = ni;
             return true;
         }
 
@@ -3895,7 +3900,7 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
             float f;
             if (ef->stringToValue(this, c, f))
             {
-                onto.f = limit_range(f, val_min.f, val_max.f);
+                ontoThis.f = limit_range(f, val_min.f, val_max.f);
                 return true;
             }
         }
@@ -3921,7 +3926,7 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
             return false;
         }
 
-        onto.f = res;
+        ontoThis.f = res;
         return true;
 
         break;
@@ -3980,7 +3985,7 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
         {
             return false;
         }
-        onto.f = res;
+        ontoThis.f = res;
         return true;
         break;
     }
@@ -4004,7 +4009,7 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
             return false;
         }
 
-        onto.f = nv;
+        ontoThis.f = nv;
         return true;
     }
     break;
@@ -4018,7 +4023,7 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
         {
             return false;
         }
-        onto.f = nv;
+        ontoThis.f = nv;
         return true;
     }
     break;
@@ -4029,7 +4034,7 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
             float uv = std::atof(c) / 440.f;
             float n = log2(uv) * 12 + 69;
             float bpv = (n - 69) / 69.f;
-            onto.f = bpv * 16 + 16;
+            ontoThis.f = bpv * 16 + 16;
         }
         else
         {
@@ -4071,7 +4076,7 @@ bool Parameter::set_value_from_string_onto(std::string s, pdata &onto)
                     nv = (nv - 1) * 16.f / 31.f + 16;
                 }
             }
-            onto.f = nv;
+            ontoThis.f = nv;
         }
     }
     break;
diff --git a/src/common/Parameter.h b/src/common/Parameter.h
index 43f04a7b95e..682d32d3d4c 100644
--- a/src/common/Parameter.h
+++ b/src/common/Parameter.h
@@ -413,8 +413,8 @@ class Parameter
     float value_to_normalized(float value);
     float get_default_value_f01();
     void set_value_f01(float v, bool force_integer = false);
-    bool set_value_from_string(std::string s);
-    bool set_value_from_string_onto(std::string s, pdata &ontoThis);
+    bool set_value_from_string(const std::string &s);
+    bool set_value_from_string_onto(const std::string &s, pdata &ontoThis);
 
     /*
      * These two functions convert the modulation depth to a -1,1 range appropriate
diff --git a/src/common/SkinColors.h b/src/common/SkinColors.h
index d7d9d0f8933..c759a7fdf8e 100644
--- a/src/common/SkinColors.h
+++ b/src/common/SkinColors.h
@@ -17,8 +17,8 @@ namespace Skin
 {
 struct Color
 {
-    Color(std::string name, int r, int g, int b);
-    Color(std::string name, int r, int g, int b, int a);
+    Color(const std::string &name, int r, int g, int b);
+    Color(const std::string &name, int r, int g, int b, int a);
 
     static Color colorByName(const std::string &name);
     static std::vector<Color> getAllColors();
diff --git a/src/common/SkinModel.h b/src/common/SkinModel.h
index 49ebf7c0387..8cc52aad13a 100644
--- a/src/common/SkinModel.h
+++ b/src/common/SkinModel.h
@@ -294,7 +294,7 @@ struct Connector
 
     Connector &asJogPlusMinus() noexcept;
 
-    Connector &withProperty(Component::Properties p, std::string v)
+    Connector &withProperty(Component::Properties p, const std::string &v)
     {
         payload->properties[p] = v;
         return *this;
diff --git a/src/common/SkinModelImpl.cpp b/src/common/SkinModelImpl.cpp
index ea473445df5..1949937a5b7 100644
--- a/src/common/SkinModelImpl.cpp
+++ b/src/common/SkinModelImpl.cpp
@@ -277,12 +277,13 @@ std::vector<Connector> Connector::connectorsByComponentType(const Component &c)
     return res;
 }
 
-Color::Color(std::string name, int r, int g, int b) : name(name), r(r), g(g), b(b), a(255)
+Color::Color(const std::string &name, int r, int g, int b) : name(name), r(r), g(g), b(b), a(255)
 {
     guaranteeMap();
     colMap->insert(std::make_pair(name, *this));
 }
-Color::Color(std::string name, int r, int g, int b, int a) : name(name), r(r), g(g), b(b), a(a)
+Color::Color(const std::string &name, int r, int g, int b, int a)
+    : name(name), r(r), g(g), b(b), a(a)
 {
     guaranteeMap();
     colMap->insert(std::make_pair(name, *this));
diff --git a/src/common/SurgeSynthesizer.cpp b/src/common/SurgeSynthesizer.cpp
index bdfb24f0da1..0d32bc42466 100644
--- a/src/common/SurgeSynthesizer.cpp
+++ b/src/common/SurgeSynthesizer.cpp
@@ -36,7 +36,7 @@
 
 using namespace std;
 
-SurgeSynthesizer::SurgeSynthesizer(PluginLayer *parent, std::string suppliedDataPath)
+SurgeSynthesizer::SurgeSynthesizer(PluginLayer *parent, const std::string &suppliedDataPath)
     : storage(suppliedDataPath), hpA(&storage), hpB(&storage), _parent(parent), halfbandA(6, true),
       halfbandB(6, true), halfbandIN(6, true)
 {
diff --git a/src/common/SurgeSynthesizer.h b/src/common/SurgeSynthesizer.h
index 374f566234c..d1a42e3c9f2 100644
--- a/src/common/SurgeSynthesizer.h
+++ b/src/common/SurgeSynthesizer.h
@@ -65,7 +65,7 @@ class alignas(16) SurgeSynthesizer
         virtual void surgeParameterUpdated(const ID &, float) = 0;
         virtual void surgeMacroUpdated(long macroNum, float) = 0;
     };
-    SurgeSynthesizer(PluginLayer *parent, std::string suppliedDataPath = "");
+    SurgeSynthesizer(PluginLayer *parent, const std::string &suppliedDataPath = "");
     virtual ~SurgeSynthesizer();
     void playNote(char channel, char key, char velocity, char detune);
     void releaseNote(char channel, char key, char velocity);
diff --git a/src/gui/SkinSupport.cpp b/src/gui/SkinSupport.cpp
index e9fdf1433c1..31d56024e26 100644
--- a/src/gui/SkinSupport.cpp
+++ b/src/gui/SkinSupport.cpp
@@ -719,9 +719,10 @@ bool Skin::reloadSkin(std::shared_ptr<SurgeImageStore> bitmapStore)
     return true;
 }
 
-bool Skin::setAllCapsProperty(std::string propertyValue)
+bool Skin::setAllCapsProperty(const std::string &propertyValueA)
 {
     // make the property value not case sensitive
+    auto propertyValue = propertyValueA;
     std::transform(propertyValue.begin(), propertyValue.end(), propertyValue.begin(),
                    [](unsigned char c) { return std::tolower(c); });
 
@@ -735,9 +736,10 @@ bool Skin::setAllCapsProperty(std::string propertyValue)
     }
 }
 
-juce::Font::FontStyleFlags Skin::setFontStyleProperty(std::string propertyValue)
+juce::Font::FontStyleFlags Skin::setFontStyleProperty(const std::string &propertyValueA)
 {
     // make the property value not case sensitive
+    auto propertyValue = propertyValueA;
     std::transform(propertyValue.begin(), propertyValue.end(), propertyValue.begin(),
                    [](unsigned char c) { return std::tolower(c); });
 
@@ -759,9 +761,10 @@ juce::Font::FontStyleFlags Skin::setFontStyleProperty(std::string propertyValue)
     }
 }
 
-juce::Justification Skin::setJuceTextAlignProperty(std::string propertyValue)
+juce::Justification Skin::setJuceTextAlignProperty(const std::string &propertyValueA)
 {
     // make the property value not case sensitive
+    auto propertyValue = propertyValueA;
     std::transform(propertyValue.begin(), propertyValue.end(), propertyValue.begin(),
                    [](unsigned char c) { return std::tolower(c); });
 
diff --git a/src/gui/SkinSupport.h b/src/gui/SkinSupport.h
index 348cbcd556e..bb509a761ea 100644
--- a/src/gui/SkinSupport.h
+++ b/src/gui/SkinSupport.h
@@ -115,9 +115,9 @@ class Skin
 #endif
     }
 
-    static bool setAllCapsProperty(std::string propertyValue);
-    static juce::Font::FontStyleFlags setFontStyleProperty(std::string propertyValue);
-    static juce::Justification setJuceTextAlignProperty(std::string propertyValue);
+    static bool setAllCapsProperty(const std::string &propertyValue);
+    static juce::Font::FontStyleFlags setFontStyleProperty(const std::string &propertyValue);
+    static juce::Justification setJuceTextAlignProperty(const std::string &propertyValue);
 
     std::string root;
     std::string name;
@@ -385,9 +385,9 @@ class Skin
 
         Type type;
         ColorStore() : type(COLOR), color(juce::Colours::black) {}
-        ColorStore(juce::Colour c) : type(COLOR), color(c) {}
-        ColorStore(std::string a) : type(ALIAS), alias(a) {}
-        ColorStore(std::string a, Type t) : type(t), alias(a) {}
+        ColorStore(const juce::Colour &c) : type(COLOR), color(c) {}
+        ColorStore(const std::string &a) : type(ALIAS), alias(a) {}
+        ColorStore(const std::string &a, Type t) : type(t), alias(a) {}
     };
     std::unordered_map<std::string, ColorStore> colors;
     std::unordered_map<std::string, int> imageStringToId;
diff --git a/src/gui/SurgeGUIEditor.cpp b/src/gui/SurgeGUIEditor.cpp
index a1900b1430e..4ae20af7b2d 100644
--- a/src/gui/SurgeGUIEditor.cpp
+++ b/src/gui/SurgeGUIEditor.cpp
@@ -1765,7 +1765,7 @@ void SurgeGUIEditor::showTuningMenu(const juce::Point<int> &where,
     });
 }
 
-void SurgeGUIEditor::scaleFileDropped(std::string fn)
+void SurgeGUIEditor::scaleFileDropped(const string &fn)
 {
     try
     {
@@ -1778,7 +1778,7 @@ void SurgeGUIEditor::scaleFileDropped(std::string fn)
     }
 }
 
-void SurgeGUIEditor::mappingFileDropped(std::string fn)
+void SurgeGUIEditor::mappingFileDropped(const string &fn)
 {
     try
     {
@@ -3517,23 +3517,23 @@ std::string SurgeGUIEditor::helpURLFor(Parameter *p)
     return "";
 }
 
-std::string SurgeGUIEditor::helpURLForSpecial(std::string key)
+std::string SurgeGUIEditor::helpURLForSpecial(const string &special)
 {
     auto storage = &(synth->storage);
-    return helpURLForSpecial(storage, key);
+    return helpURLForSpecial(storage, special);
 }
 
-std::string SurgeGUIEditor::helpURLForSpecial(SurgeStorage *storage, std::string key)
+std::string SurgeGUIEditor::helpURLForSpecial(SurgeStorage *storage, const std::string &special)
 {
-    if (storage->helpURL_specials.find(key) != storage->helpURL_specials.end())
+    if (storage->helpURL_specials.find(special) != storage->helpURL_specials.end())
     {
-        auto r = storage->helpURL_specials[key];
+        auto r = storage->helpURL_specials[special];
         if (r != "")
             return r;
     }
     return "";
 }
-std::string SurgeGUIEditor::fullyResolvedHelpURL(std::string helpurl)
+std::string SurgeGUIEditor::fullyResolvedHelpURL(const string &helpurl)
 {
     std::string lurl = helpurl;
     if (helpurl[0] == '#')
diff --git a/src/gui/SurgeGUIEditor.h b/src/gui/SurgeGUIEditor.h
index 93fa0616e68..ed0639c8d0c 100644
--- a/src/gui/SurgeGUIEditor.h
+++ b/src/gui/SurgeGUIEditor.h
@@ -275,8 +275,8 @@ class SurgeGUIEditor : public Surge::GUI::IComponentTagValue::Listener,
 
     void toggleMPE();
     void toggleTuning();
-    void scaleFileDropped(std::string fn);
-    void mappingFileDropped(std::string fn);
+    void scaleFileDropped(const std::string &fn);
+    void mappingFileDropped(const std::string &fn);
     std::string tuningToHtml();
 
     void modSourceButtonDroppedAt(Surge::Widgets::ModulationSourceButton *msb,
@@ -356,7 +356,7 @@ class SurgeGUIEditor : public Surge::GUI::IComponentTagValue::Listener,
 
     std::string getDisplayForTag(long tag);
 
-    void queuePatchFileLoad(std::string file)
+    void queuePatchFileLoad(const std::string &file)
     {
         strncpy(synth->patchid_file, file.c_str(), FILENAME_MAX);
         synth->has_patchid_file = true;
@@ -589,10 +589,11 @@ class SurgeGUIEditor : public Surge::GUI::IComponentTagValue::Listener,
 
   public:
     std::string helpURLFor(Parameter *p); // this requires internal state so doesn't have statics
-    std::string helpURLForSpecial(std::string special); // these can be either this way or static
+    std::string
+    helpURLForSpecial(const std::string &special); // these can be either this way or static
 
-    static std::string helpURLForSpecial(SurgeStorage *, std::string special);
-    static std::string fullyResolvedHelpURL(std::string helpurl);
+    static std::string helpURLForSpecial(SurgeStorage *storage, const std::string &special);
+    static std::string fullyResolvedHelpURL(const std::string &helpurl);
 
   private:
     void promptForUserValueEntry(Parameter *p, juce::Component *c, int modulationSource = -1);
diff --git a/src/gui/SurgeGUIUtils.cpp b/src/gui/SurgeGUIUtils.cpp
index 960f172029a..c67c4e09898 100644
--- a/src/gui/SurgeGUIUtils.cpp
+++ b/src/gui/SurgeGUIUtils.cpp
@@ -8,7 +8,7 @@ namespace Surge
 namespace GUI
 {
 
-std::string toOSCaseForMenu(std::string menuName)
+std::string toOSCaseForMenu(const std::string &menuName)
 {
 #if WINDOWS
     for (auto i = 1; i < menuName.length() - 1; ++i)
diff --git a/src/gui/SurgeGUIUtils.h b/src/gui/SurgeGUIUtils.h
index d8b0a99ee4e..49f59229296 100644
--- a/src/gui/SurgeGUIUtils.h
+++ b/src/gui/SurgeGUIUtils.h
@@ -8,7 +8,7 @@ namespace Surge
 {
 namespace GUI
 {
-std::string toOSCaseForMenu(std::string menuName);
+std::string toOSCaseForMenu(const std::string &menuName);
 
 extern bool showCursor(SurgeStorage *storage);
 
diff --git a/src/gui/SurgeImage.cpp b/src/gui/SurgeImage.cpp
index a1de78c3e65..8c559e149b5 100644
--- a/src/gui/SurgeImage.cpp
+++ b/src/gui/SurgeImage.cpp
@@ -29,7 +29,7 @@ SurgeImage::SurgeImage(int rid)
     }
 }
 
-SurgeImage::SurgeImage(std::string fname)
+SurgeImage::SurgeImage(const std::string &fname)
 {
     this->fname = fname;
     drawable = juce::Drawable::createFromImageFile(juce::File(fname));
@@ -62,7 +62,7 @@ void SurgeImage::setPhysicalZoomFactor(int zoomFactor)
     }
 }
 
-void SurgeImage::addPNGForZoomLevel(std::string fname, int zoomLevel)
+void SurgeImage::addPNGForZoomLevel(const std::string &fname, int zoomLevel)
 {
     pngZooms[zoomLevel] = std::make_pair(fname, nullptr);
 }
diff --git a/src/gui/SurgeImage.h b/src/gui/SurgeImage.h
index 9dafe92fd0b..9404ad5cefa 100644
--- a/src/gui/SurgeImage.h
+++ b/src/gui/SurgeImage.h
@@ -16,10 +16,10 @@ class SurgeImage
 {
   public:
     SurgeImage(int resourceId);
-    SurgeImage(std::string fname);
+    SurgeImage(const std::string &fname);
     ~SurgeImage();
 
-    void addPNGForZoomLevel(std::string fname, int zoomLevel);
+    void addPNGForZoomLevel(const std::string &fname, int zoomLevel);
     void resolvePNGForZoomLevel(int zoomLevel);
     void setPhysicalZoomFactor(int zoomFactor);
 
diff --git a/src/gui/UIInstrumentation.cpp b/src/gui/UIInstrumentation.cpp
index afdcdbecd69..c8edb67a8ac 100644
--- a/src/gui/UIInstrumentation.cpp
+++ b/src/gui/UIInstrumentation.cpp
@@ -15,7 +15,7 @@ namespace Debug
 {
 std::unordered_map<std::string, std::atomic<int>> records;
 
-void record(std::string tag) { records[tag]++; }
+void record(const std::string &tag) { records[tag]++; }
 void report()
 {
     std::ostringstream oss;
@@ -34,7 +34,7 @@ void report()
     Surge::UserInteractions::showHTML(oss.str());
 }
 
-TimeThisBlock::TimeThisBlock(std::string i) : tag(i)
+TimeThisBlock::TimeThisBlock(const std::string &i) : tag(i)
 {
     start = std::chrono::high_resolution_clock::now();
 }
diff --git a/src/gui/UIInstrumentation.h b/src/gui/UIInstrumentation.h
index 50099312d90..b69d8fc904e 100644
--- a/src/gui/UIInstrumentation.h
+++ b/src/gui/UIInstrumentation.h
@@ -13,7 +13,7 @@ namespace Debug
 /*
 ** Just count how many times we hit this function
 */
-void record(std::string tag);
+void record(const std::string &tag);
 
 /*
 ** Pop up the timing report in a browser
@@ -29,7 +29,7 @@ void report();
 */
 struct TimeThisBlock
 {
-    TimeThisBlock(std::string tag);
+    TimeThisBlock(const std::string Ytag);
     ~TimeThisBlock();
     std::string tag;
     std::chrono::time_point<std::chrono::high_resolution_clock> start;