diff --git a/src/Mod/Path/PathScripts/PathInspect.py b/src/Mod/Path/PathScripts/PathInspect.py
index 448bc6b685..19cc291a78 100644
--- a/src/Mod/Path/PathScripts/PathInspect.py
+++ b/src/Mod/Path/PathScripts/PathInspect.py
@@ -112,7 +112,6 @@ class GCodeEditorDialog(QtGui.QDialog):
         font.setPointSize(p.GetInt("FontSize", 10))
         self.editor.setFont(font)
         self.editor.setText("G01 X55 Y4.5 F300.0")
-        self.highlighter = GCodeHighlighter(self.editor.document())
         layout.addWidget(self.editor)
 
         # Note
@@ -192,11 +191,25 @@ class GCodeEditorDialog(QtGui.QDialog):
 
 def show(obj):
     "show(obj): shows the G-code data of the given Path object in a dialog"
-
+    
+    prefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Path")
+    # default Max Highlighter Size = 512 Ko
+    defaultMHS = 512 * 1024 
+    mhs = prefs.GetUnsigned('inspecteditorMaxHighlighterSize', defaultMHS)
+    
     if hasattr(obj, "Path"):
         if obj.Path:
             dia = GCodeEditorDialog(obj.Path)
             dia.editor.setText(obj.Path.toGCode())
+            gcodeSize = len(dia.editor.toPlainText())
+            if (gcodeSize <= mhs):
+                # because of poor performance, syntax highlighting is 
+                # limited to mhs octets (default 512 KB).
+                # It seems than the response time curve has an inflexion near 500 KB
+                # beyond 500 KB, the response time increases exponentially.
+                dia.highlighter = GCodeHighlighter(dia.editor.document())
+            else:
+                FreeCAD.Console.PrintMessage(translate("Path", "GCode size too big ({} o), disabling syntax highlighter.".format(gcodeSize)))
             result = dia.exec_()
             # exec_() returns 0 or 1 depending on the button pressed (Ok or
             # Cancel)
diff --git a/src/Mod/Path/PathScripts/PostUtils.py b/src/Mod/Path/PathScripts/PostUtils.py
index 26f6ba491e..5acadafc79 100644
--- a/src/Mod/Path/PathScripts/PostUtils.py
+++ b/src/Mod/Path/PathScripts/PostUtils.py
@@ -78,7 +78,6 @@ class GCodeEditorDialog(QtGui.QDialog):
         font.setPointSize(10)
         self.editor.setFont(font)
         self.editor.setText("G01 X55 Y4.5 F300.0")
-        self.highlighter = GCodeHighlighter(self.editor.document())
         layout.addWidget(self.editor)
 
         # OK and Cancel buttons
@@ -134,8 +133,23 @@ def fmt(num,dec,units):
 
 def editor(gcode):
     '''pops up a handy little editor to look at the code output '''
+    
+    prefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Path")
+    # default Max Highlighter Size = 512 Ko
+    defaultMHS = 512 * 1024 
+    mhs = prefs.GetUnsigned('inspecteditorMaxHighlighterSize', defaultMHS)
+    
     dia = GCodeEditorDialog()
     dia.editor.setText(gcode)
+    gcodeSize = len(dia.editor.toPlainText())
+    if (gcodeSize <= mhs):
+        # because of poor performance, syntax highlighting is 
+        # limited to mhs octets (default 512 KB).
+        # It seems than the response time curve has an inflexion near 500 KB
+        # beyond 500 KB, the response time increases exponentially.
+        dia.highlighter = GCodeHighlighter(dia.editor.document())
+    else:
+        FreeCAD.Console.PrintMessage(translate("Path", "GCode size too big ({} o), disabling syntax highlighter.".format(gcodeSize)))
     result = dia.exec_()
     if result:  # If user selected 'OK' get modified G Code
         final = dia.editor.toPlainText()