Whoa there champ, you cant just come here and start demanding things and complaining and making comparisons to other handheld consoles which I prefer to leave unnamed. There are many reasons why quake runs like, as you so subtly put it "total donkey poo". First of all, its a new port, and does not take full advantage of the hardware. Also, the 3d rendering is being done with software rendering, since the GP2X only has a 2d graphics card. Also, I believe it is only using one of the two processors, so it would run kind of slowly then.
About MAME, some games will run well, others won't. Theres a whole handy dandy thread on this, you just gotta do a little searching.