If you have HLSL enabled, disable it for that game. That will make a pretty big difference.
If you have a 64-bit operating system, using the 64 bit version of MAME gains you some performance on that driver.
There's also an option in the dip switch settings to run the game at a lower resolution, which makes it less demanding.
These don't make a huge difference, but it may be the difference between having sound skips or not.
Blitz is one of the most desired "processor hogs" along with Gauntlet Legends.
Pretty much any 3D game from the mid 90's forward is going to require at 3.5Ghz+ depending on the model of processor.