When playing a video in PS, FPS suddenly dropping

Hi

Photoshop is not really a video editor, it is an image editor with some video functions added on. You do not say what format the video is, but I suspect it is something like H.264 which is very efficient for storage but puts a high load on an editor to play back in real time whilst editing. In a video editor such as Premiere Pro, video to be edited can be converted to proxy files in a format that is much easier to play back in real time. 

All that said, with only 8GB RAM and an i3 processor you are going to struggle with real time playback, regardless of which editor you choose, and you may just need to wait until it renders before playing back the second time through as suggested by Kevin earlier.

Dave

On such a weak computer I wouldn't expect anything to be realtime, to be honest. This looks very much normal. You have very limited RAM and on top of it probably the GPU acceleration is nothing to write home about on your budget notebook or whatever this is. It's simply unrealistic to expect it to do video editing with all the frills.

Mylenium

Its because its trying to render the preview as it's playing.

After it renders it will play smoother, however 8GB RAM is the bare minimum.

If you are editing larger video files, this will be used up in no time and cause other issues.