i tried this emulator last week, because everyone said, it was faster than zerlurkers one.

i tried it with Metal Slug 1, set it to 333MHz, but it was way slower than zerlurkers. massive slowdowns when many explosions where on the screen, no fun anymore.
strange, in NJ's emu, there's no option for using the GPU, is it default?

but anyways, many updates and upcoming savestates sound very promising.