In the yee old'en days, only the length of opcode would make much of a difference or if it were implemented in a slightly different microcode path which would c

In the yee old'en days, only the length of opcode would make much of a difference or if it were implemented in a slightly different microcode path which would change the number of micro-ops slightly. Reg aliasing/renaming I think would make transfers between registers very fast unless a data hazard existed in subsequent/branch-predicted instructions (scheduling the "liveness" in the register file across the pipeline stages so it doesn't mess anything up). PS: Hehe.. anyone remember U/V pipe optimization? :) Michael Abrash books on assembly and 3D game programming, and assembly profiling on real hardware FTW.