I don't think that the OP is necessarily saying that there are ~mainstream languages that are faster than C; just that C is far from optimal when it comes to sp

I don't think that the OP is necessarily saying that there are ~mainstream languages that are faster than C; just that C is far from optimal when it comes to speed and how much it can be optimized. "Not that fast" doesn't necessarily mean that it isn't the fastest we have got.