Incredibly, choosing to install SF4's stages onto the PS3 hard drive cuts load times by over 50%. This is a must do if you play online. Requires both players to have already Installed it to see the shortness of loading times. If one player didn't Install and you did, you'll have to wait for him to finish loading the stage. Here's how to do it.

From the main menu:

OPTIONS / SYSTEM SETTINGS / INSTALL

It takes a few minutes, but well worth it. You'll notice the difference in online play (if other player installed it) and in offline.