Hello,

I have done some tests with git master and on my system the bgfx vulkan backend is not really faster than opengl one - it is faster than non-bgfx opengl though. This is quite in contrast to ~30 fold speedup RB was mentioning with GTX 1080. My system is equipped with an RTX 2070 and is running Fedora 31.
bgfx vulkan:
Code
$ ./mame64 -rompath /mnt/openmediavault/emu/mame/roms/ -window -nomaximize -video bgfx -bgfx_backend vulkan umk3 -sdlvideofps
  0.02s,    1 F, avrg game: 54.70 FPS 18.28 ms/f, avrg video: 9713.08 FPS 0.10 ms/f, last video:   inf FPS 0.05 ms/f
  1.02s,   56 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 11416.83 FPS 0.09 ms/f, last video:   inf FPS 0.06 ms/f
  2.03s,  111 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 11262.14 FPS 0.09 ms/f, last video:   inf FPS 0.05 ms/f
  3.03s,  166 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 12902.32 FPS 0.08 ms/f, last video:   inf FPS 0.05 ms/f
  4.04s,  221 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 13949.67 FPS 0.07 ms/f, last video:   inf FPS 0.05 ms/f
  5.05s,  276 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 14693.42 FPS 0.07 ms/f, last video:   inf FPS 0.05 ms/f
  6.05s,  331 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 15231.93 FPS 0.07 ms/f, last video:   inf FPS 0.05 ms/f
  7.06s,  386 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 15622.80 FPS 0.06 ms/f, last video:   inf FPS 0.06 ms/f
  8.06s,  441 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 15902.47 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
  9.07s,  496 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 16151.91 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
 10.07s,  551 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 16362.50 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
 11.08s,  606 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 16483.35 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
 12.08s,  661 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 16670.53 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
 13.09s,  716 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 16799.59 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
 14.09s,  771 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 16933.72 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
 15.10s,  826 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 16994.24 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
 16.10s,  881 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 17045.69 FPS 0.06 ms/f, last video:   inf FPS 0.06 ms/f
 17.11s,  936 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 17126.95 FPS 0.06 ms/f, last video:   inf FPS 0.06 ms/f
 18.11s,  991 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 17222.62 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
 19.12s, 1046 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 17282.82 FPS 0.06 ms/f, last video:   inf FPS 0.05 ms/f
Average speed: 100.00% (19 seconds)

bgfx opengl:
Code
$ ./mame64 -rompath /mnt/openmediavault/emu/mame/roms/ -window -nomaximize -video bgfx -bgfx_backend opengl umk3 -sdlvideofps
  0.02s,    1 F, avrg game: 54.69 FPS 18.29 ms/f, avrg video: 12423.75 FPS 0.08 ms/f, last video:   inf FPS 0.04 ms/f
  1.02s,   56 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 23462.81 FPS 0.04 ms/f, last video:   inf FPS 0.04 ms/f
  2.03s,  111 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 23951.68 FPS 0.04 ms/f, last video:   inf FPS 0.04 ms/f
  3.03s,  166 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 23751.12 FPS 0.04 ms/f, last video:   inf FPS 0.04 ms/f
  4.04s,  221 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 23580.58 FPS 0.04 ms/f, last video:   inf FPS 0.04 ms/f
  5.05s,  276 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 20869.75 FPS 0.05 ms/f, last video:   inf FPS 0.03 ms/f
  6.05s,  331 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 21497.07 FPS 0.05 ms/f, last video:   inf FPS 0.04 ms/f
  7.06s,  386 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 22042.05 FPS 0.05 ms/f, last video:   inf FPS 0.04 ms/f
  8.06s,  441 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 22386.92 FPS 0.04 ms/f, last video:   inf FPS 0.03 ms/f
  9.07s,  496 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 22647.45 FPS 0.04 ms/f, last video:   inf FPS 0.04 ms/f
 10.07s,  551 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 22781.78 FPS 0.04 ms/f, last video:   inf FPS 0.03 ms/f
 11.08s,  606 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 22819.63 FPS 0.04 ms/f, last video:   inf FPS 0.10 ms/f
 12.08s,  661 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 22979.21 FPS 0.04 ms/f, last video:   inf FPS 0.03 ms/f
 13.09s,  716 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 23045.63 FPS 0.04 ms/f, last video:   inf FPS 0.03 ms/f
 14.09s,  771 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 23188.50 FPS 0.04 ms/f, last video:   inf FPS 0.04 ms/f
 15.10s,  826 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 23204.76 FPS 0.04 ms/f, last video:   inf FPS 0.04 ms/f
Average speed: 100.00% (16 seconds)

non-bgfx opengl:
Code
$ ./mame64 -rompath /mnt/openmediavault/emu/mame/roms/ -window -nomaximize -video opengl umk3 -sdlvideofps
  0.02s,    1 F, avrg game: 54.72 FPS 18.27 ms/f, avrg video: 3456.94 FPS 0.29 ms/f, last video:   inf FPS 0.14 ms/f
  1.02s,   56 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6689.12 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
  2.03s,  111 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6581.31 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
  3.03s,  166 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6571.33 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
  4.04s,  221 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6471.70 FPS 0.15 ms/f, last video:   inf FPS 0.14 ms/f
  5.05s,  276 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6530.33 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
  6.05s,  331 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6572.34 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
  7.06s,  386 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6606.00 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
  8.06s,  441 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6627.62 FPS 0.15 ms/f, last video:   inf FPS 0.14 ms/f
  9.07s,  496 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6643.38 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
 10.07s,  551 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6660.48 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
 11.08s,  606 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6659.45 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
 12.08s,  661 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6671.08 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
 13.09s,  716 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6669.14 FPS 0.15 ms/f, last video:   inf FPS 0.14 ms/f
 14.09s,  771 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6681.80 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
 15.10s,  826 F, avrg game: 54.71 FPS 18.28 ms/f, avrg video: 6692.23 FPS 0.15 ms/f, last video:   inf FPS 0.15 ms/f
Average speed: 100.00% (16 seconds)

Am I doing something wrong?