"rep stosb" has been optimized since Ivy Bridge CPUs. > Beginning with processors based on Ivy Bridge microarchitecture, REP string operation using MOVSB and S

"rep stosb" has been optimized since Ivy Bridge CPUs. > Beginning with processors based on Ivy Bridge microarchitecture, REP string operation using MOVSB and STOSB can provide both flexible and high-performance REP string operations for software in common situations like memory copy and set operations. > Beginning with processors based on Ice Lake Client microarchitecture, REP MOVSB performance of short operations is enhanced. The enhancement applies to string lengths between 1 and 128 bytes long. * https://www-ssl.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-optimization-manual.html https://www-ssl.intel.com/content/www/us/en/architecture-and... * https://stackoverflow.com/a/33485055 https://stackoverflow.com/a/33485055