Why is memcmp so much faster than a for loop check?

Question

Why is memcmp(a, b, size) so much faster than:

for(i = 0; i < nelements; i++) {
    if a[i] != b[i] return 0;
}
return 1;

I

Answer 1

It's usually a compiler intrinsic that is translated into fast assembly with specialized instructions for comparing blocks of memory.

intrinsic memcmp