Photoshop running very slow

Ever since the last few updates PS has been running really slow.  Even after a fresh installis still does it.  Its when you use the rubber tool.  So if I paste part of a image onto another and rub out the edges to blend in the whole app lags.  It never used to and I have not changed any of the settings.  Using the PS Beta aswell and it is fine.  Not sure what to do or change.  Or just stop using it and keep using the Beta.