Videos slow down at 720p

I try to import very small files (less than 50MB with about a minute of footage at 720p) and yet the video still lags. I have gone through several videos trying to fix this but to no avail. I really have no idea what the problem is because after checking the amount of skipped frames while playing the video on photoshop there were none. When I also decided to export the video with many stutters it kept those stutters at export. I do only have 8GB of RAM but I figured that would not have been an issue with such low-resolution videos. I'm slowly starting to feel buyer's remorse and I have only just bought the application less than an hour ago. Somebody, please help.