Why is my FPS so low?
There are a number of reasons why your SDL application might have a low FPS. Here are a few reasons and solutions:
Vertical Sync might be turned on. Change your display settings to disable Vertical Sync. See FAQ_Vertical_Sync.
Your SDL_Surface surfaces that are being blitted may be a different format to the surface of your screen. Look at SDL_ConvertSurface to convert surfaces to your main surface, you may also use SDL_DisplayFormat.
You might want to try OpenGL with SDL. It takes advantage of your video card's hardware acceleration.