BIG PROBLEM WITH AFTER EFFECTS(2019)

So, I have a big problem with After Effects - I have 2019 verison. So I recently wanted to make a few changes - I had problems with my audio and also wanted to make my colours different. So I checked in YouTube for tutorials and after a few changes in the settings I succeded. But when I started editing, I found a new serious problem - the transitions were very laggy. I mean, when I make even a simple keyframe transition, for example scale it doesn`t just go smoothly(it`s supposed to be), it comes torn and in parts like I stop it in every movement and I can`t do nothingg(same with blurmocurves). Looks like I changed some options while I was fixing the audio ot else. PLEASE help me!!!!

I will attach a video to see how it is because I didn`t explain it well.