It probably has a true ARM9 processor in a System-on-a-Chip at 195 Mhz instead of say, an Xscale at 312 or ~400 Mhz (speeds typical to XScales.) As a general rule, XScales generally perform at about 50% the speed of a true ARM9 at the same clockrate. Many reviewers were baffled when 400 Mhz PocketPC units started flooding the market and showed no significant performance gains over 200 Mhz ARM9 units...
That said, the PocketPC emulation scene is a mess. There are 3 MegaDrive/Genesis emulators I tried; one is slow and doesn't work on most units, and was last updated over a year ago. MorphGear is abysmally slow, and doesn't even approach 60 FPS with sound even with a ~500 Mhz XScale proc (250 Mhz ARM9 equivalent performance). With sound off, it gets SOMEWHAT close. PicoDrive is very fast but has no sound and it's scaled miserably. Also it has massive compatibility issues like drawing all the dolphins in random orientation on the screen in Ecco 1/2 .. the developer told me he maybe intended to update it in the future, if he has time.
Full speed MD Emulation on the GP2X with sound is a reality at the stock 200 MHz ...
NES emulation was better but even then the controls on any PocketPC I tried (or any smartphone for that matter) are really pitiful for it. Clicking navigation pads, not d-pads, too few buttons, shitty cramped orientation .. it just doesn't work.
Despite DaveC's comments that SNES emulation is superior on PocketPCs to the GP2X, that sure wasn't my experience. At ~500 MHz XScale clock performance was nowhere near 60 FPS. Not even close. I've sure as hell never seen a working Neogeo emulator-- the MAME port for PocketPC has no NeoGeo support at all. Good GB emulators exist, I'll admit that, and there are enough buttons for that. But the d-pad still sucked enough to make it hard to tolerate those ...