Everything cannot be important. If you say that maintainability, extensibility, legibility etc. etc. is more important than performance then you are, in fact,

Everything cannot be important. If you say that maintainability, extensibility, legibility etc. etc. is more important than performance then you are, in fact, saying that performance is NOT important. But those are mostly just the excuses that Casey is ranting about. There's nothing inherent in writing fast code that makes is not maintainable, not extensible, not legible not etc., not etc. In fact, the things that make code less maintainable and less legible are often the things that make is slower. Things like replacing new Foo() with FooFactory and replacing FooFactory with FooFactoryProvider and then encoding logic in XML files. Those are things that people do way more often that writing SIMD intrinsic. And there are those who way overemphasize supposed "legibility" over performance. In JavaScript land you get legion claiming that the world will end if they rewrite unnecessarily slow map(), filter(), forEach() etc. with a regular for loop.