I am using a SyntaxEditor, from ActiproSoftware.SyntaxEditor.Net20.dll v4.0.287.0 library. I opened syntax editor instance and start pasting code, after 5000 pasted strings I call _editor.SelectedView.FindReplace.MarkAll(options, typeof(SelectedWordIndicator)); method. And every time when I call this method it's work slow. But after I reopen _editor document it starts work much faster. I already tried to clear UndoRedo buffer, but it doesn't help.