diff --git a/code/AssetLib/3MF/XmlSerializer.cpp b/code/AssetLib/3MF/XmlSerializer.cpp
index 9bd1c5bb0..740bc5658 100644
--- a/code/AssetLib/3MF/XmlSerializer.cpp
+++ b/code/AssetLib/3MF/XmlSerializer.cpp
@@ -106,7 +106,7 @@ bool getNodeAttribute(const XmlNode &node, const std::string &attribute, int &va
     return false;
 }
 
-aiMatrix4x4 parseTransformMatrix(std::string matrixStr) {
+aiMatrix4x4 parseTransformMatrix(const std::string& matrixStr) {
     // split the string
     std::vector<float> numbers;
     std::string currentNumber;
diff --git a/code/AssetLib/Blender/BlenderLoader.cpp b/code/AssetLib/Blender/BlenderLoader.cpp
index b3591b4f1..2ed0d6b8a 100644
--- a/code/AssetLib/Blender/BlenderLoader.cpp
+++ b/code/AssetLib/Blender/BlenderLoader.cpp
@@ -281,7 +281,7 @@ void BlenderImporter::ExtractScene(Scene &out, const FileDatabase &file) {
 }
 
 // ------------------------------------------------------------------------------------------------
-void BlenderImporter::ParseSubCollection(const Blender::Scene &in, aiNode *root, std::shared_ptr<Collection> collection, ConversionData &conv_data) {
+void BlenderImporter::ParseSubCollection(const Blender::Scene &in, aiNode *root, const std::shared_ptr<Collection>& collection, ConversionData &conv_data) {
 
     std::deque<Object *> root_objects;
     // Count number of objects
diff --git a/code/AssetLib/Blender/BlenderLoader.h b/code/AssetLib/Blender/BlenderLoader.h
index 0299ae393..b29ee5941 100644
--- a/code/AssetLib/Blender/BlenderLoader.h
+++ b/code/AssetLib/Blender/BlenderLoader.h
@@ -117,7 +117,7 @@ protected:
     void InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) override;
     void ParseBlendFile(Blender::FileDatabase &out, std::shared_ptr<IOStream> stream);
     void ExtractScene(Blender::Scene &out, const Blender::FileDatabase &file);
-    void ParseSubCollection(const Blender::Scene &in, aiNode *root, std::shared_ptr<Blender::Collection> collection, Blender::ConversionData &conv_data);
+    void ParseSubCollection(const Blender::Scene &in, aiNode *root, const std::shared_ptr<Blender::Collection>& collection, Blender::ConversionData &conv_data);
     void ConvertBlendFile(aiScene *out, const Blender::Scene &in, const Blender::FileDatabase &file);
 
 private:
diff --git a/code/AssetLib/IFC/IFCOpenings.cpp b/code/AssetLib/IFC/IFCOpenings.cpp
index 6b8b565c2..3c4a0b3cd 100644
--- a/code/AssetLib/IFC/IFCOpenings.cpp
+++ b/code/AssetLib/IFC/IFCOpenings.cpp
@@ -1428,7 +1428,7 @@ bool GenerateOpenings(std::vector<TempOpening>& openings,
     return true;
 }
 
-std::vector<IfcVector2> GetContourInPlane2D(std::shared_ptr<TempMesh> mesh,IfcMatrix3 planeSpace,
+std::vector<IfcVector2> GetContourInPlane2D(const std::shared_ptr<TempMesh>& mesh,IfcMatrix3 planeSpace,
     IfcVector3 planeNor,IfcFloat planeOffset,
     IfcVector3 extrusionDir,IfcVector3& wall_extrusion,bool& first,bool& ok) {
     std::vector<IfcVector2> contour;
@@ -1491,7 +1491,7 @@ static void logSegment(std::pair<IfcVector2,IfcVector2> segment) {
     IFCImporter::LogInfo(msg2.str().c_str());
 }
 
-std::vector<std::vector<IfcVector2>> GetContoursInPlane3D(std::shared_ptr<TempMesh> mesh,IfcMatrix3 planeSpace,
+std::vector<std::vector<IfcVector2>> GetContoursInPlane3D(const std::shared_ptr<TempMesh>& mesh,IfcMatrix3 planeSpace,
     IfcFloat planeOffset) {
 
         {
@@ -1676,7 +1676,7 @@ std::vector<std::vector<IfcVector2>> GetContoursInPlane3D(std::shared_ptr<TempMe
             std::stringstream msg;
             msg << "GetContoursInPlane3D: found " << contours.size() << " contours:\n";
 
-            for(auto c : contours) {
+            for(const auto& c : contours) {
                 msg << " Contour: \n";
                 for(auto p : c) {
                     msg << "   " << p.x << " " << p.y << " \n";
@@ -1690,7 +1690,7 @@ std::vector<std::vector<IfcVector2>> GetContoursInPlane3D(std::shared_ptr<TempMe
         return contours;
 }
 
-std::vector<std::vector<IfcVector2>> GetContoursInPlane(std::shared_ptr<TempMesh> mesh,IfcMatrix3 planeSpace,
+std::vector<std::vector<IfcVector2>> GetContoursInPlane(const std::shared_ptr<TempMesh>& mesh,IfcMatrix3 planeSpace,
     IfcVector3 planeNor,IfcFloat planeOffset,
     IfcVector3 extrusionDir,IfcVector3& wall_extrusion,bool& first) {
 
diff --git a/code/AssetLib/X3D/X3DImporter.cpp b/code/AssetLib/X3D/X3DImporter.cpp
index b34f361ae..01c97eb4c 100644
--- a/code/AssetLib/X3D/X3DImporter.cpp
+++ b/code/AssetLib/X3D/X3DImporter.cpp
@@ -333,7 +333,7 @@ void X3DImporter::readHead(XmlNode &node) {
     }
     mScene->mMetaData = aiMetadata::Alloc(static_cast<unsigned int>(metaArray.size()));
     unsigned int i = 0;
-    for (auto currentMeta : metaArray) {
+    for (const auto& currentMeta : metaArray) {
         mScene->mMetaData->Set(i, currentMeta.name, aiString(currentMeta.value));
         ++i;
     }