> Windows 10 LTSC + Firefox + uBlock Origin on an i5-9400 feels faster than my M4 Pro MBP

I don't remember Win10 being particularly lean (although I'm sure 11 is worse). And the M4 is definitely a much more powerful CPU. Can you not run Firefox and uBO on that? Or have they really weighed things down that much with the OS somehow?

> Probably same or better on Linux.

Even with the Cinnamon desktop environment I can vouch it uses considerably less RAM for just the desktop (ordinary applications are probably about the same) and offers much faster filesystem access by default. I'm sure this is at least partly due to not being weighed down by built-in anti-malware (that would do basically nothing for people who are comfortable using Linux in the first place).