I did exactly that (well, almost that - I downclocked my Phenom II to 1.7GHz and disabled all but one core) when I wrote my first commercial app back in 2016.

I did exactly that (well, almost that - I downclocked my Phenom II to 1.7GHz and disabled all but one core) when I wrote my first commercial app back in 2016. It ran great with a few optimisations (or more specifically, removal of some really dumb code). It seemed really obvious to me to ensure it would run well on a broad array of old hardware, and I suspect this is because of all the time spent on OCAU as a teenager trying to get the cheapest hardware possible to play the latest games.