Grant has a Fast CPU selection which allows the user to press the F1 key to toggle between Slow and Fast CPU choices. 

0 (power-up default) will set the CPU to 1MHz (standard UK101 speed). Pressing the F1 key will switch it to 12.5MHz ( ! ) and pressing F1 again will switch it back.

It patches the CEGMON location that does the timing loop for the repeat key. It's worth installing. A 12.5 MHz UK101/Ohio Scientific C1P is pretty cool.