Kodi sometimes takes 1 second to start a video, other times 10 seconds

Hi. Wondering what is causing this.

This problem been forever, from kodi v17 or lower to v21. Windows.

You can see on the video, the same videos sometimes takes forever to start and is not usable at all. Is not an storage speed problem at all.

Videos are mp4 from mame video snaps and usualy are low res 512×480 5mb files.