Can anyone play NFL blitz or Crusing USA
I have a 2600 GHZ 3d card and 512 megs of ram and they are too slow to play. What other games are in mame but really can't be played?
Most of the newer and .chd games require a lot of horsepower.
What you might try doing is underclocking the processors on the tilde menu. I can get near 100% framerate on crusin USA with a Pentium 1.8 Ghz PC with both CPU's underclocked to 10% (although I'm not sure what effect this has on playability).
See
http://www.arcadecontrols.org/yabbse/index.php?board=3;action=display;threadid=18170 for details on ways to set MAME up to automatically use a set underclock when games are started.
As far as why the games are so slow - Consider the following - PacMan ran on a 3.07 Mhz CPU (slightly slower than the original IBM PC). MAME could not play it on a 286 or 386, somewhere between a 486-100 and a Pentium 200, it became playable. Cruisin is using a 50 Mhz CPU and some of the newer games are basically using roughly a Pentium 200 class CPU in the game itself.
The math isn't this simple, but just on clock speed, crusin is running 16.66 times faster than PacMan so it should require a 200x16.66 = 3.3 Ghz machine to run. (This does not take into account processor advances beyond clock speed).
As far as why MAME doesn't use hardware acceleration - it's all about accuracy. In most cases the original games did not use sophisticated polygon drawing routines and 3d optimizations, so for MAME to use them, it would be SIMULATING the game, instead of EMULATING it.
It would be neat to see an emulator which took advantage of modern 3D cards, but it will be less authentic, it will be difficult to come up with, and it will probably be independent of MAME.