Is interesting, you can click on the left button in the demo below as quickly as you like and all runs smoothly. Click on the right one and the response is slow and jerky. #include <GuiConstants.au3> $Main_GUI = GuiCreate("", 160, 80) GUISetFont (9, 600, 0) $Button_Left = GUICtrlCreateButton("<", 20, 20) $Label = GUICtrlCreateLabel("", 60, 25, 20, 20) $Button_Right = GUICtrlCreateButton(">", 100, 20) GuiCtrlSetColor(-1, 0x0000FF); blue ;GuiCtrlSetBkColor(-1, 0xFFFFFF); white GUISe