Don't optimize something that's not performance critical

Reason

Optimizing a non-performance-critical part of a program has no effect on system performance.

Note

If your program spends most of its time waiting for the web or for a human, optimization of in-memory computation is probably useless.

Put another way: If your program spends 4% of its processing time doing computation A and 40% of its time doing computation B, a 50% improvement on A is only as impactful as a 5% improvement on B. (If you don't even know how much time is spent on A or B, see <a href="#rper-reason">Per.1</a> and <a href="#rper-knuth">Per.2</a>.)