> Is unoptimized code really that bad? Absolutely. Compilers can't do much about poor locality and most code is not written with locality in mind. And in man

> Is unoptimized code really that bad? Absolutely. Compilers can't do much about poor locality and most code is not written with locality in mind. And in many cases locality isn't really much of an option anyway; for instance, think about a key-value dictionary much larger than cache, responding to random requests. People have contrived ways of trying to make these cache-friendly but they generally end up slower than a really well-optimized hash lookup. You can improve it further in some cases by using prefetching extensively and trading memory bandwidth for latency, but as the article points out that can actually be a really terrible idea. So without further knowledge of the workload there just isn't a lot you can do.