diff --git a/src/libs/vdxf/libdxfrw/drw_entities.h b/src/libs/vdxf/libdxfrw/drw_entities.h
index fa34584ba..79095fb35 100644
--- a/src/libs/vdxf/libdxfrw/drw_entities.h
+++ b/src/libs/vdxf/libdxfrw/drw_entities.h
@@ -664,7 +664,7 @@ public:
             delete item;
     }
     void applyExtrusion() override;
-    void addVertex(DRW_Vertex2D v)
+    void addVertex(const DRW_Vertex2D &v)
     {
         auto *vert = new DRW_Vertex2D();
         vert->x = v.x;
@@ -917,7 +917,7 @@ public:
         for (DRW_Vertex *item : vertlist)
             delete item;
     }
-    void addVertex(DRW_Vertex v)
+    void addVertex(const DRW_Vertex& v)
     {
         auto *vert = new DRW_Vertex();
         vert->basePoint.x = v.basePoint.x;
diff --git a/src/libs/vdxf/libdxfrw/drw_header.cpp b/src/libs/vdxf/libdxfrw/drw_header.cpp
index 017a60cc4..bac771819 100644
--- a/src/libs/vdxf/libdxfrw/drw_header.cpp
+++ b/src/libs/vdxf/libdxfrw/drw_header.cpp
@@ -1831,7 +1831,7 @@ void DRW_Header::write(const std::unique_ptr<dxfWriter> &writer, DRW::Version ve
 #endif
 }
 
-void DRW_Header::addDouble(std::string key, double value, int code)
+void DRW_Header::addDouble(const std::string &key, double value, int code)
 {
     curr = new DRW_Variant();
     curr->addDouble(value);
@@ -1839,7 +1839,7 @@ void DRW_Header::addDouble(std::string key, double value, int code)
     vars[key] = curr;
 }
 
-void DRW_Header::addInt(std::string key, int value, int code)
+void DRW_Header::addInt(const std::string &key, int value, int code)
 {
     curr = new DRW_Variant();
     curr->addInt(value);
@@ -1847,7 +1847,7 @@ void DRW_Header::addInt(std::string key, int value, int code)
     vars[key] = curr;
 }
 
-void DRW_Header::addStr(std::string key, const std::string &value, int code)
+void DRW_Header::addStr(const std::string &key, const std::string &value, int code)
 {
     curr = new DRW_Variant();
     curr->addString(value);
@@ -1855,7 +1855,7 @@ void DRW_Header::addStr(std::string key, const std::string &value, int code)
     vars[key] = curr;
 }
 
-void DRW_Header::addCoord(std::string key, const DRW_Coord &value, int code)
+void DRW_Header::addCoord(const std::string &key, const DRW_Coord &value, int code)
 {
     curr = new DRW_Variant();
     curr->addCoord(value);
diff --git a/src/libs/vdxf/libdxfrw/drw_header.h b/src/libs/vdxf/libdxfrw/drw_header.h
index a6f4b92df..092b325c6 100644
--- a/src/libs/vdxf/libdxfrw/drw_header.h
+++ b/src/libs/vdxf/libdxfrw/drw_header.h
@@ -107,10 +107,10 @@ public:
        return *this;
     }
 
-    void addDouble(std::string key, double value, int code);
-    void addInt(std::string key, int value, int code);
-    void addStr(std::string key, const std::string &value, int code);
-    void addCoord(std::string key, const DRW_Coord &value, int code);
+    void addDouble(const std::string &key, double value, int code);
+    void addInt(const std::string &key, int value, int code);
+    void addStr(const std::string &key, const std::string &value, int code);
+    void addCoord(const std::string &key, const DRW_Coord &value, int code);
     auto getComments() const -> std::string { return comments; }
     void write(const std::unique_ptr<dxfWriter>& writer, DRW::Version ver);
     void addComment(const std::string &c);
diff --git a/src/libs/vdxf/libdxfrw/intern/dxfwriter.cpp b/src/libs/vdxf/libdxfrw/intern/dxfwriter.cpp
index 0b12cf874..abdd92d24 100644
--- a/src/libs/vdxf/libdxfrw/intern/dxfwriter.cpp
+++ b/src/libs/vdxf/libdxfrw/intern/dxfwriter.cpp
@@ -105,7 +105,7 @@ auto dxfWriter::writeUtf8Caps(int code, const std::string &text) -> bool
     return writeString(code, t);
 }
 
-auto dxfWriterBinary::writeString(int code, std::string text) -> bool
+auto dxfWriterBinary::writeString(int code, const std::string &text) -> bool
 {
     char bufcode[2];
     bufcode[0] = static_cast<char>(code & 0xFF);
@@ -227,7 +227,7 @@ dxfWriterAscii::dxfWriterAscii(std::ofstream *stream):dxfWriter(stream){
     filestr->precision(16);
 }
 
-auto dxfWriterAscii::writeString(int code, std::string text) -> bool
+auto dxfWriterAscii::writeString(int code, const std::string &text) -> bool
 {
     //    *filestr << code << std::endl << text << std::endl ;
     filestr->width(3);
diff --git a/src/libs/vdxf/libdxfrw/intern/dxfwriter.h b/src/libs/vdxf/libdxfrw/intern/dxfwriter.h
index 8bbd4b5ac..934f9f66f 100644
--- a/src/libs/vdxf/libdxfrw/intern/dxfwriter.h
+++ b/src/libs/vdxf/libdxfrw/intern/dxfwriter.h
@@ -25,7 +25,7 @@ public:
     }
 
     virtual ~dxfWriter() = default;
-    virtual auto writeString(int code, std::string text) -> bool = 0;
+    virtual auto writeString(int code, const std::string &text) -> bool = 0;
     auto writeUtf8String(int code, const std::string &text) -> bool;
     auto writeUtf8Caps(int code, const std::string &text) -> bool;
     auto fromUtf8String(const std::string &t) -> std::string { return encoder.fromUtf8(t); }
@@ -52,7 +52,7 @@ public:
     using dxfWriter::dxfWriter;
 
     virtual ~dxfWriterBinary() = default;
-    virtual auto writeString(int code, std::string text) -> bool override;
+    virtual auto writeString(int code, const std::string &text) -> bool override;
     virtual auto writeInt16(int code, int data) -> bool override;
     virtual auto writeInt32(int code, int data) -> bool override;
     virtual auto writeInt64(int code, unsigned long long int data) -> bool override;
@@ -65,7 +65,7 @@ class dxfWriterAscii final : public dxfWriter
 public:
     explicit dxfWriterAscii(std::ofstream *stream);
     virtual ~dxfWriterAscii() = default;
-    virtual auto writeString(int code, std::string text) -> bool override;
+    virtual auto writeString(int code, const std::string &text) -> bool override;
     virtual auto writeInt16(int code, int data) -> bool override;
     virtual auto writeInt32(int code, int data) -> bool override;
     virtual auto writeInt64(int code, unsigned long long int data) -> bool override;
diff --git a/src/libs/vdxf/libdxfrw/libdxfrw.cpp b/src/libs/vdxf/libdxfrw/libdxfrw.cpp
index 5d6799146..fbbe8b4fe 100644
--- a/src/libs/vdxf/libdxfrw/libdxfrw.cpp
+++ b/src/libs/vdxf/libdxfrw/libdxfrw.cpp
@@ -1685,7 +1685,7 @@ auto dxfRW::writeImage(DRW_Image *ent, const std::string &name) -> DRW_ImageDef
     return nullptr; // not exist in acad 12
 }
 
-auto dxfRW::writeBlockRecord(std::string name) -> bool
+auto dxfRW::writeBlockRecord(const std::string &name) -> bool
 {
     if (version > DRW::AC1009)
     {
diff --git a/src/libs/vdxf/libdxfrw/libdxfrw.h b/src/libs/vdxf/libdxfrw/libdxfrw.h
index 0c55f5b91..6daa11c10 100644
--- a/src/libs/vdxf/libdxfrw/libdxfrw.h
+++ b/src/libs/vdxf/libdxfrw/libdxfrw.h
@@ -69,7 +69,7 @@ public:
     auto writeLWPolyline(DRW_LWPolyline *ent) -> bool;
     auto writePolyline(DRW_Polyline *ent) -> bool;
     auto writeSpline(DRW_Spline *ent) -> bool;
-    auto writeBlockRecord(std::string name) -> bool;
+    auto writeBlockRecord(const std::string &name) -> bool;
     auto writeBlock(DRW_Block *bk) -> bool;
     auto writeInsert(DRW_Insert *ent) -> bool;
     auto writeMText(DRW_MText *ent) -> bool;
diff --git a/src/libs/vgeometry/vsplinepoint_p.h b/src/libs/vgeometry/vsplinepoint_p.h
index 6f2e05330..f6016c7b9 100644
--- a/src/libs/vgeometry/vsplinepoint_p.h
+++ b/src/libs/vgeometry/vsplinepoint_p.h
@@ -90,7 +90,7 @@ class VSplinePointData final : public QSharedData
 {
 public:
     VSplinePointData() = default;
-    VSplinePointData(VPointF pSpline, qreal angle1, const QString &angle1F, qreal angle2, const QString &angle2F,
+    VSplinePointData(const VPointF &pSpline, qreal angle1, const QString &angle1F, qreal angle2, const QString &angle2F,
                      qreal length1, const QString &length1F, qreal length2, const QString &length2F);
     VSplinePointData(const VSplinePointData &point);
     ~VSplinePointData() = default;
@@ -119,7 +119,7 @@ private:
 };
 
 //---------------------------------------------------------------------------------------------------------------------
-inline VSplinePointData::VSplinePointData(VPointF pSpline, qreal angle1, const QString &angle1F, qreal angle2,
+inline VSplinePointData::VSplinePointData(const VPointF &pSpline, qreal angle1, const QString &angle1F, qreal angle2,
                                           const QString &angle2F, qreal length1, const QString &length1F, qreal length2,
                                           const QString &length2F)
   : pSpline(pSpline),
diff --git a/src/test/ValentinaTest/tst_vabstractcurve.cpp b/src/test/ValentinaTest/tst_vabstractcurve.cpp
index 0adaf4a51..c5457c86f 100644
--- a/src/test/ValentinaTest/tst_vabstractcurve.cpp
+++ b/src/test/ValentinaTest/tst_vabstractcurve.cpp
@@ -178,7 +178,7 @@ void TST_VAbstractCurve::CurveIntersectLine_data()
     QTest::addColumn<QVector<QPointF>>("intersections");
     QTest::addColumn<QLineF>("line");
 
-    auto ASSERT_TEST_CASE = [](const char *title, const QString &input, const QString &output, QLineF line)
+    auto ASSERT_TEST_CASE = [](const char *title, const QString &input, const QString &output, const QLineF &line)
     {
         QVector<QPointF> const points = AbstractTest::VectorFromJson<QPointF>(input);
         QVector<QPointF> const intersections = AbstractTest::VectorFromJson<QPointF>(output);