I just edited my first Video, it was a highlight from a Streamer. I downloaded the video file and while working with it, I noticed some frames randomly jerking. I had no problems with my fps but randomly the whole screen just jerks. You can even see it in the yt video here:
since I got it from a Guide off of LinkedIn Learning - don't be so sure, use MediaInfo tool to check. Regardless of that, you can also try to disable Preferences > Media > hardware accelerated decoding', and set renderer to 'sotfware only'