Gab75 not at all inefficient, to properly emulate the ula for multicolor mode it will have to be quite a bit more involved, just like the nes emulation - if you want a perfect ppu, you'll have to run single cycle at a time. When writing the nes and spectrum emu's from scratch I went for the perfection rather than speed on ancient pc's. On the other hand, I did test, and my nes and spectrum emulation runs at full speed on my old p4 2.9ghz (windows says 2.9, it's really a 3ghz cpu)
Here's why it's wrong to compare any game with 68k as main processor, with the nes and spectrum emulation:
For example, system32 runs a frame like this:
[top of frame]
run cpus
draw screen
[end of frame]
nes and spectrum are quite a bit more involved..
[top of frame]
(repeat this ~70,000 times for zx or ~20,000 times for nes)
run 1 cycle cpu
run ppu(nes) or ula(zx)
[end of frame]
best regards,
- dink