What do you mean by that? You don't lose gaming performance when you use win10 over win11. Why would you?
There are 2 components, the background and the slides. I didn't touch most of the slides, because I realized they would need more than a simple upscale. The ones I did upscale I used waifu2x for. For everything else I used waifu2x, GIMP and Paint.NET.
waifu2x was an okay upscaler back in 2018. Today I would use StableSR or SUPIR.
I never finished it, but I think I was the only one doing higher res versions of the menu background and intro slides almost from scratch.
Another guy upscaled most of the slides, their mod is linked in the description.
One reason I'm thankful for Obtainium is because "OAuth was not approved by Google, etc for the F-Droid build" of Fair Email, and unfortunately, that's still important for me. Obtainium is able to download from the official F-droid repo too.
The guide is on the site they linked. It works, I did it a few times. They have to mirror the LTSC installation files unfortunately, but there's a guide on how to verify they're genuine if you don't trust them.