alt Hacker NewsAre you serious? Of course you can. Some hash algorithms are slower than others, you can read that and know that. Allocating in a hot loop is probably slower than allocating outside of it. Duh? I can't believe this even has to be justified, of course you can look at code and get an idea of its performance properties lol
Obviously you want empirical evidence to justify changes, but like... duh, you can read code and understand how it executes.
Sometimes when you look at code you know is slow, you can immediately see why it's slow. Obviously you didn't see it when you wrote it, which disproves your hypothesis.