Comment by ocdtrekkie
5 years ago
I think another place people can end up here is if they don't know what the compiler is doing under the hood, it's easy to assume the shortest code will perform the fastest or something like that. "Presumably this cool trick avoids these extra steps" type of things.
Before I had written much assembly, I used to think ifs to avoid assignments was smart. Turns out avoiding branching is better for both testability and performance.
A similar thing I've noticed a trend of recently in frontend react codebases is overuse of memoization. It seems as though people don't realize how it works and that it is often _less_ performant than just doing some low cost computation on each render (like a comparison or basic math).