A shocking amount, but in a many cases its also what doesn't exist, or isn't optimized. C is designed to be a lowest common denominator language. So, the whole

A shocking amount, but in a many cases its also what doesn't exist, or isn't optimized. C is designed to be a lowest common denominator language. So, the whole flat memory model, large register machines, single stack registers. When you look at all the things people think are "crufty" about x86, its usually through the lenses of "modern" computing. Things like BCD, fixed point, capabilities, segmentation, call gates, all the odd 68000 addressing modes, etc. Many of those things that were well supported in other environments but ended up hindering or being unused by C compilers. On the other side you have things like inc/dec two instructions which influence the idea of the unary ++ and -- rather than the longer more generic forms. So while the latency of inc is possibly the same as add, it still has a single byte encoding.