Why is the editor lagging anyway to fix it?

i move my mouse around its fine but it takes a few seconds for the engine to realize where my cursor is and the UI is laggy as well. whats odd is when i have the file options open or so it doesnt happen its normal. please help.

I have this same issue with a project in ue4.11.2 it only starts to lag after first time i press play and exit the “game”, and i basically have to shut down the editor to make any more changes. So it seems related to my particular project because i dont get this lagging behavior with some other projects. So something has been corrupted somehow. Any way i can provide info to Epic to troubleshoot this?