Most fun I ever had with a 6502 was when I realized that, at 1 MHz, I could do 250,000 average instructions per second. So I divided my monitor up into 20 boxes to have 12500 (fairly complex!) instructions per per second for each box. I used them to separately animate the contents of each box differently.

Just calculating or shuffling data around was invisible. With that visualization I first realized how much stuff could be done with a 1MHz CPU.