There were several speeds of the V20, including the base version at 5Mhz. Using it as a drop-in replacement and keeping the system clock speed the same the NEC

There were several speeds of the V20, including the base version at 5Mhz. Using it as a drop-in replacement and keeping the system clock speed the same the NEC V20 would still give you a 15 to 20% performance bump because it used less clock cycles when executing many insgtructions. (This machine has not been altered to speed the clock.)