Quote: "a 1Ghz CPU to emulate an 8Mhz processor ?! (or 16 for the GBA)"
Yes, at the moment it does require a 1Ghz CPU to run 100% unfortunately a lot of the time seems to be actually spent in refreshing the screen as the way a Gameboy handles screen drawing is different than how you would update the screen (it renders each line separately with a BG, Window, and Sprite layer and then during the V-BLANK period we get to draw the screen. If you were making a game in DBP you wouldn't have commands to render every single line, you'd place a bitmap background, toss another bitmap over that, place your sprites on the screen and sync for the end result.
This is actually only achieving this speed thanks largly in part to finding ways to optimize coding in DBP. It used to take 20 seconds to emulate 1 Second of CPU time. (Even longer earlier in development)
I've virtually eliminated all WHILE ENDWHILE statements with IF FOR NEXT ENDIF structures and replaced the whole DO LOOP with a FOR NEXT loop that never exits (unless told to...) These two things actually had the most dramatic increase in speed.
Sound is one thing that hasn't been implemented yet as it also will require a bit of work to handle. Again, we'd just normally load a WAV or MP3 and type play sound 1 and you have sound but the Gameboy sets registers to determine what sound is generated on which channel.
With a CPU, video, and sound hardware being emulated with one piece of software which has to translate it all to work with DBP, a computer's CPU, video and sound.
Also, keep in mind that even for the CPU it can take a few lines of code to emulate a single CPU intstruction.
