lots of single core programs utilize 100% of a core.
back in my tinkering 2006-08 days i got war2.ru to do online with a 386 33 mhz. editing the sprites to framskip in a mpq editor and making the tileset all black. so anyone with a old comp and want to mess with it there is some fun to be had
sory had a flashback
(edit) pre 2000 programs maybe be more correct i know lots of my old games do but the newer single seem to throttle. would be a nice fix