Not pretending to have any experience in writing emulators, but VBA emulates an ARM processor. Both the GBA and the 770/N800 have one, so this step is quite useless, slowing the program down (quite a lot).
If you want to bypass this step, I think you have to rewrite most of the program (~15% of the VBA code is ARM emulation).
Then again, I could of course be completely wrong and it's actually a trivial task.