System Information
Operating system: Windows-10-10.0.19042-SP0 64 Bits
Graphics card: Intel(R) UHD Graphics Intel 4.5.0 - Build 27.20.100.9664

Blender Version
Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: rBf1cca3055776
Worked: (newest version of Blender that worked as expected)

Short description of error
There is a steady decline of the VSE performance when editing a video, and can only be resolved by closing and reopening blender

Exact steps for others to reproduce the error
While editing videos in the VSE,
doing just a basic cut, muting and deleting of video strips,
after a while, there is a noticeable drop in performance,
the playback become laggy (even with a scene using 50% proxy)
and editing (moving of strips also start to lag).

The only solution has been to save the scene, close and reopen blender, and the playback goes back to 30 fps, but within a few minutes, I notice the Lag again.

Here's a recording that shows the difference in performance, when I close and reopen blender