First program I ever wrote on a Sinclair Spectrum was to spin a disk on the screen.

I was disappointed with the performance, so for the second program I precalculated the sin/cos values and stored them in an array (and learnt that all programming is an exercise in caching).

I was still disappointed with the performance, so the third program I wrote was a hex loader so I could poke machine code straight into it (had to run down to the local electronics store to pick up copy of the Z80 assembler manual). I then was happy with the speed.

That kickstarted a career in software development which I still derive immense enjoyment from.