The only game that seems to run flawlessly for snes is Super Mario World... 0 _ 0
This has got to be a joke.
Either you have the old SNEStyl, or you downloaded only 3 games. First off, download snestyl ME edition, which boosts your FPS a lot. I can run Super Mario Kart, and even Star Ocean at almost perfect speeds. I also configured my own little code for Super Mario RPG so battles run at 30+ FPS, though there are some slowdowns in the field depending on how many monsters are in that area. Those are probably the only games that lag for me.
Super Metroid owns on the PSP, btw.
You can also update the snesadvance.dat off of the website of the developer. It will support almost every SNES game made, and improves the FPS in the current ones.
microsoft word document: Well, I wouldn't recommend a PSP Slim, since it not going to be hackable unless you have a Pandora battery, which must be made using the fat PSP. Plus, the kernels for the slim aren't fully made yet, so half of the homebrew isn't even going to work on it. As for setting the whole thing up, first you're going to need a PSP that has a firmware lower than 3.50(around there). You can then purchase Lumines(hoping they haven't patched it yet) and downgrade using the illuminati exploit. Google that if you don't know what it is. The other option is just purchasing a Pandora battery on ebay or something, which will automatically downgrade to 1.50 for you, but I'm not sure you want to go that route.
Once you're in 1.50, you can pretty much upgrade to any firmware you want. I would recommend 3.52 M33-4. It's just as stable as the 3.40, and you get a lot more features.