Some generally older software has buggy multi threading implementation, and forcing its threads to execute “interleaved, but never simultaneously” often improves stability or even completely hides the issue.
Also I know some games used to have big performance issues if they had too many hardware threads available, but I don’t know why exactly
Is it real that Arch users are rich and have mid level PCs and is always up to date?
I do have a powerful desktop running Arch (or rather EndeavourOS with the EndeavourOS packages slowly removed over time), but also a 15 year old netbook. There’s plenty of up-to-date lightweight software in Arch repos, you don’t need to limit yourself to old software.
Also it’s not like a new version of GIMP is suddenly going to use double the memory if you use the same tools in it.
The biggest issue for the netbook is web browsing, but that’s just about web pages being resource hogs nowadays. uBlock Origin and NoScript help massively. Trying to use an old web browser is IMHO a terrible idea - you’ll end up with broken pages and a massive pile of security vulnerabilities.
Wayland does force clients to be able to cope with a compositor that doesn’t do SSD - CSD support is mandatory, SSD optional.
Not sure if that’s your case as well, but I remember that there was an issue with Intel Bay Trail tablets where the BIOS/UEFI was 32bit but the CPU could support 64bit OS just fine. You just need to get a special bootloader that will boot 64bit Linux kernel from a 32bit UEFI (which is not normally supported)
Here’s one reference https://github.com/dmotte/misc/blob/main/knowledge/linux-x64-grub-uefi-32bit/README.md - it should be possible for you to use a 64bit Debian, but you’ll need to get your hands dirty.