[UE 4.12.5]Respon Time Error

so today i redown my project from UE 4.24 to 4.12 by Rework on the project too old i wold say but yea i prefer that version however since the latest update of ue 4.12.5 the editor not respond well
pressing button giving delay of 4 sec to show, 1 minutes to delete assets depend how much i delete for example 1 assets is 1 min, folder is like 20 min before you say something my pc is very high performance and i try it on my brother pc too and i don’t know what to do.