The problem there is I don’t have it installed from steam. I downloaded the plutonium torrent game for BO1. Would verifying on steam still help at all?

When I play a map with a cutscene like Five or Call of the Dead, the cutscene lags, stutters, stops and skips around insanely bad. Then once the cutscene finishes, it’s just a black screen for about a minute and then it finally loads up and the gameplay is smoother than butter. I don’t understand why pre-rendered cutscenes which are really just video files would lag so much, and yet the gameplay is totally fine? Is there any fix for this?