plugins-extra VS Bulk-Crap-Uninstaller

Or Process Hacker (https://processhacker.sourceforge.io/) which IMO is even better.

I can use Process Hacker and run "Reduce working set" on it, which makes explorer.exe instantly go down to ~100MB. However, it just starts leaking RAM again and it's a matter of hours until it grows back to several GB.

I can't have a task manager style tool installed? It's completely safe and does NOTHING in terms of cheating, no other game has ever flagged it as false positive. Is this AC so bad that it sees the word "h4Ck3R" and thinks it needs to be removed? What else is this thing needlessly scanning my computer for?

you need Process Hacker

You mean this? https://processhacker.sourceforge.io/

http://www.lucashale.com/timer-resolution/ set to maximum https://processhacker.sourceforge.io/ Set valheim.exe priority to high and save it.

If you are on the latest BIOS, the next thing I'd be looking at is something that's hitting I/O, either use Process Hacker: https://processhacker.sourceforge.io/ or task manager to try and catch the process causing the problem.

Please use a decent task manager like Process hacker or Task manager deluxe, the Windows one is kinda lacking functionality.

Is it sluggish in the current state ? Have you tried to do a 'real' complete uninstall using BC-Uninstaller, deleting all the leftovers in the registry that might be corrupted or sth ?

It's not exactly a debloater, but https://www.bcuninstaller.com/ will help you to get rid of majority of bloatware. It's not automatic unfortunately, you need to know what you're doing.

Try this: https://github.com/Klocman/Bulk-Crap-Uninstaller

try uninstalling via BCUninstaller and reboot your PC afterwards.

Bulk Crap Uninstaller

BulkCrap Uninstaller works well when it comes to uninstalling things and finding leftovers.