But most programs are somehow still really slow! And when you look into why, the reason is always something like this. The code was either written by juniors and never optimized because they don’t know how, or written by mids at the limit of their intelligence. And full of enough complex abstractions that nobody on the team can reason holistically about how the whole program works. Then things get slow at a macro level because fixing it feels hard.
Either way it’s all avoidable. The only thing that makes your old computer feel sluggish for everyday computing is that programmers got faster computers, and then got lazy, and then shipped you crappy software.