Why I Maintain a 17 Year Old Thinkpad https://pilledtexts.com/why-i-use-a-17-year-old-thinkpad/
#NixOS is interesting. Pretty reliable (not as much as #AtomicDesktops in my noob tests) while also performant
Note that such old hardware will have #microcode vulnerabilities and locking it down will further slow it down. At least thinking of #spectre or #meltdown (not sure if hyperthreading was even thought of back then)