How to keep the CPU usage down while running an SDL program?

I would definitely experiment with fully blocking functions (such as SDL_WaitEvent). I have an OpenGL application in Qt, and I noticed the CPU usage hovers between 0% and 1%. It spikes to maybe 4% during "usage" (moving the camera and/or causing animations).

I am working on my own windowing toolkit. I have noticed I can achieve similar CPU usage when I use blocking event loops. This will complicate any timers you may depend on, but it is not terribly difficult to implement timers with this new approach.

I know this is an older post, but I myself just came across this issue with SDL when starting up a little demo project. Like user 'thebuzzsaw' noted, the best solution is to use SDL_WaitEvent to reduce the CPU usage of your event loop.

Here's how it would look in your example for anyone looking for a quick solution to it in the future. Hope it helps!

#include "SDL.h"
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;

int main(int argc, char **argv)
{
    SDL_Init( SDL_INIT_VIDEO );
    SDL_Surface* screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, 0, 
                                            SDL_HWSURFACE | SDL_DOUBLEBUF );
    SDL_WM_SetCaption( "SDL Test", 0 ); 
    SDL_Event event;
    bool quit = false;
    while (quit == false)
    {
        if (SDL_WaitEvent(&event) != 0) {
            switch (event.type) {
            case SDL_QUIT:
            quit = true;
            break;
            }
        }
    }
    SDL_Quit();
    return 0;
}