[gorilla0]

We often hear that choosing the right algorithm will get rid of all performance problems. There is no "need" to understand what is happening under the hood and all programmers should only work at higher levels of abstraction.

My take away from this question and and the top answer was that the above is not true. It does not mean that everyone has to code using assembly - it means that good programmers are aware of where their abstractions may leak.

Related reading (can't believe it's almost 20 years since this article was written) - https://www.joelonsoftware.com/2002/11/11/the-law-of-leaky-a...

[inglor_cz]

Knowing the character of your data is priceless. The only time I was able to throughly beat GCC with optimizations is when I knew that most 32-bit values being calculated upon are actually fairly small (in tens of thousands) and that I could use that to my advantage.