-sdlvideofps will give an idea how performant your video output is. Running an HP9000/320 on my MacBook, it says this:

Code
  0.01s,    1 F, avrg game: 68.78 FPS 14.54 ms/f, avrg video: 414.14 FPS 2.41 ms/f, last video:   inf FPS 1.26 ms/f
  1.03s,   72 F, avrg game: 70.02 FPS 14.28 ms/f, avrg video: 708.18 FPS 1.41 ms/f, last video:   inf FPS 1.18 ms/f
  2.03s,  142 F, avrg game: 69.98 FPS 14.29 ms/f, avrg video: 700.22 FPS 1.43 ms/f, last video:   inf FPS 2.07 ms/f
  3.04s,  213 F, avrg game: 70.01 FPS 14.28 ms/f, avrg video: 719.18 FPS 1.39 ms/f, last video:   inf FPS 1.15 ms/f
  4.06s,  284 F, avrg game: 70.00 FPS 14.29 ms/f, avrg video: 735.14 FPS 1.36 ms/f, last video:   inf FPS 1.47 ms/f
  5.07s,  355 F, avrg game: 70.00 FPS 14.28 ms/f, avrg video: 738.10 FPS 1.35 ms/f, last video:   inf FPS 1.19 ms/f

The "avrg game" is the core emulation's frame rate (this system is a computer putting out a 1024x768@70 Hz screen, so the 70.00 once it settles in is correct), and "avrg video" shows how fast MAME would run if all it did was upload frames in the current configuration. With decent GL drivers that should be above 300%; if it's much below that you might have problems.