AFAIK, memcpy is not a simple loop, in a way that it can align the copies to match the architecture. For example, with the right conditions (aligned memory), it

AFAIK, memcpy is not a simple loop, in a way that it can align the copies to match the architecture. For example, with the right conditions (aligned memory), it can copy 32 or 64 bits at a time for most of the loop, and the remaining through copies of 8 bits (not specifically in that order). You don't replace memcpy unless you do it right. The difference between systems with a bad or good memcpy is abysmal.