As I type this I am not sure what to do... In my project I am moving still PNG's without any effects on a 1080p timeline. I have a decently specced computer (I7-6700K 4GHz, 32GB RAM, GTX 1080 GPU, SSD edit drive) . But whenever I try to stretch the clip on the timeline or move clips. The whole computer crawls to a slog. I'm talking about 10-30 seconds between moving the edit point until Premiere shows me the result. It is like running with 16 ton weights on my shoes. I searched around and found that the culprit seems to be the dreaded option for "Composite Preview During Trim". I disabled that and the editing suddenly went at light speed... for a while...
Then. Randomly I get the same issue again. But when I check the option for the Composite Preview... it's disabled. Just like I left it. But when I do edits... the program monitor shows trying to do the Composite view nonetheless with the dual playbacks... WHY?! I disabled it for a reason! Why can't I disable it until adobe fixes it? The problem seems old because the forums that talk about the solution are several years old. Why not adress it?!
I also have this issue. Composite Preview During Trim switch doesn't work. It always pops up and slows down my editing workflow A LOT. Adobe please fix. Will send a bug notice - I encourage everyone to do the same.
Not sure I could be specced any higher for this type of thing and its still slow to switch in and out of composite preview. Horrible.