Thumbnails generate really slowly

[inmate4850]

Linux Mint Mate 20.2 x86_64
Kernel 5.11.0

I've tried several file managers from caja, nemo, dolphin, nautilus, and pcmanfm but the only one that generated thumbnails in every folder at a reasonable speed, like in windows, was pcmanfm-qt. Unfortunately, I cannot use this file manager because it has other issues that were dealbreakers, as with all the others. (I forgot what issues because this was so long ago and I just stuck with nemo).

Nemo does generate thumbnails in all folders but for some (such as a folder full of videos on an unencrypted veracrypt drive) it's super slow (several minutes to generate a few thumbnails), and sometimes it flat out doesn't. I tried waiting for the thumbnails to show up for all files but once I refreshed the window, they were all gone and it had to start over as if none of them were cached. It also occasionally doesn't generate a thumbnail for new files so I have to clear the cache, refresh the window, and then it will generate it. This became so common that I had to create a bash script and attach a hotkey to it.

[all41]

If you have a large number of thumbnails then you may need to increase the size
of the thumbnail cache.
https://davejansen.com/increase-thumbna ... in-ubuntu/

[inmate4850]

I changed it from 512 to 4096 but it didn't change anything. Something I forgot to mention before was that it also doesn't display the correct aspect ratio for videos that are 9:16 unless I import them into a video editor and export them as 9:16 (which they already were).