> I mean, what kind of horsepower did the old
> arcade machines have? Surely they are not more powerful than a $200 nettop PC? I
> realize they were machines dedicated to a single task, whereas computers are not and
> they must emulate. But still. AdvanceMAME, as old as it is, can still play many ROMs
> and runs fine on low-end hardware. Why can't MAME, what's so different about it?
The development of MAME over the years has been dedicated to the goal of accuracy and portability, not performance, and the level of accuracy desired by authors can increase over the years without necessarily having end-user-noticeable benefits.
Example: The most recent version of AdvanceMAME likely used compressed audio samples (WAV files) to reproduce the analog circuitry that produced sound in Donkey Kong. Modern MAME has an analog-audio simulation component that actually attempts to simulate this circuitry's effect, which can be rather costly in performance.
The development of AdvanceMAME has stopped. The development of MAME has continued for many years since.
You should give the FAQ a read, especially
THIS PAGE: http://mamedev.org/devwiki/index.php/FAQ:Performance