Why does my video editing playback slow down after a short amount of time? I'm fairly new to Blender and video editing as a whole. I understand that the playback in Blender's VSE needs to load a video once before playing at full framerate. After playing through a video once, when I return to the beginning, I'm able to play it smoothly at 60fps. However, after around 1000 frames, I get a brief freeze in the video followed by ~24fps playback for the remainder. The audio plays fine at full speed, not freezing with the video and finishing long before it. I've tried this with multiple different clips (flv files recorded with OBS) and the problem is consistent in each clip, though there doesn't seem to be anything wrong with the clips themselves if just played raw through a media player. Does anyone have a fix for this?
Seems likely you just run out of the buffer. Because the video frame is actually quite HUGE to computer system, the buffer of the video will be constraint at certain amount for sure to ensure available RAM.

The default setting amount can be find in Setting > System > Memory &amp; Limit: Sequencer Cache Limit



You should tune this amount depend on your RAM size. Yeah, 1024 MB is quite small for general 3D modeling available computer which usually got 16 GB or higher RAM.