It's just a much faster CPU. And like I said, timing emulation is not accurate on MAME for the 68040. It is emulated too slow. If I can make a very very rough guess, a 68040 @ 25MHz is around as fast as a 68030 @ 80MHz.

As Franz says, calculation time measurements on V10 will help, then speed can be estimated on CB-Emu with an overclock.
I think someone measured V11 already? And concluded that it is around 166MHz under emulation.