The chances are that memcpy() is faster (less expensive) because it's more frequently used, and there are plenty of "optimized memcpy" implementations out there, whilst memmove is less frequently used, so the chances are that it's slightly less optimized in the first place, and has added complexity, whcih can cause it to be slower in itself. --

memcpy_s copies count bytes from src to dest; wmemcpy_s copies count wide characters (two bytes). If the source and destination overlap, the behavior of memcpy_s is undefined. Use memmove_s to handle overlapping regions. These functions validate their parameters. Jul 05, 2016 · A. `mithril` is one of the fastest, general purpose, multi-platform (32-bit AND 64-bit) implementations I have. This is a general purpose replacement for ALL built-in memmove/memcpy implementations in ALL compilers! This function WILL outperform both Visual Studio (2010) AND GCC memmove/memcpy, as long as you have a P4 (circa 2001) or newer!