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** The microcode can employ both pipelines to enable auto-repeating instructions such as rep movsw perform one iteration every clock cycle, while the 80486 needed three clocks per iteration ( and the earliest x86-chips significantly more than the 486 ).

Also, optimization of the access to the first microcode words during the decode stages helps in making several frequent instructions execute significantly more quickly, especially in their most common forms, and in typical cases.

Some examples are ( 486 → Pentium, in clock cycles ): CALL ( 3 → 1 ), RET ( 5 → 2 ), shifts / rotates ( 2 ~ 3 → 1 ), etc.