It isn't just the PSP having a higher clock frequency, but it also takes advantage of the Media Engine chip as kind of a second CPU, albeit with some limitations.
Now, I don't want to get anyone's hopes up, but emulation on the o3DS may still improve. Having to render graphics in software is really what holds it back, imo. blargSNES does attempt to use the GPU to render everything as polygons, but there are various inaccuracies, and sometimes, it takes quite a bit of processing just to build the lists for the GPU to render. I'm hoping a more streamlined, and less intensive method will be fully devised once we understand the hardware a bit more.
Nice, are you guys still working on BlargSnes btw?