Tim Bray: I Hate My MacBook "if only it were faster. Is it possible I have a lemon?". I don't think it's a lemon. I left the Mac world a few years ago now and moved to Linux. My wife inherited my old MacBook Pro and what I've noticed is that it seems to have gotten slower and slower over time, in a way I haven't seen outside of the Apple ecosystem. I recollect the same issue with the MacBook Black I had before that. Personally I think it's a design flaw. If I temporarily release my paranoid inner conspiracy theorist, I'd say it was a purposeful design flaw... ٩(ʘ益ʘ)۶
My recommendation would be a Dell XPS running Ubuntu (or another flavour - although I didn't have such a straightforward experience when I tried to use Arch).