make vs2015 SOURCES=src\mame\drivers\astrocde.cpp SUBTARGET=gorf
It will create a new .sln file in a different directory (I don't remember off-hand so search for the file). If you build that it should be much quicker.
It looks like run to next vblank in the debugger is stopping at the start and end of vblank, which is a bug in the debugger that was introduced last year. I just pushed a fix to github. I believe the issue you are seeing is more likely to do with frame rate of pacman not being the same as the frame ...