Another good reason to write optimization-friendly C (or similar) over assembly code, especially in libraries, is that the compiler will evolve with CPUs, while

Another good reason to write optimization-friendly C (or similar) over assembly code, especially in libraries, is that the compiler will evolve with CPUs, while the assembly code will not. I've seen plenty of cases where replacing hand-written assembly with C (or similar) lead to a substantial performance increase because the assembly code was written for some old CPU and not the best way of doing things on current CPUs.