SDL2: Slow clean and update

// Includes and SDL_INIT
////////////////////////

SDL_Window *_window = SDL_CreateWindow( "Window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 800, 600, 0 );
SDL_Renderer *_renderer = SDL_CreateRenderer( _window, -1, SDL_RENDERER_ACCELERATED );

Timer fps_timer;
int fps;
SDL_Event event;
bool running = true;

fps = 0;
fps_timer.start();

// Pokud hra stále běží
while ( running ) {

    fps++;
    SDL_PollEvent( &event );

    if ( event.type == SDL_QUIT ) {
        running = false;
    }

    if ( SDL_RenderClear( _renderer ) != 0 ) {
        std::cout << "Clear fail" << std::endl;
    }

    ///////////////////
    // CODE
    ///////////////////

    SDL_RenderPresent( _renderer );

    if ( fps_timer.getTicks() >= 1000 ) {

       std::cout << "FPS: " <<  fps << std::endl;
       fps = 0;
       fps_timer.start();

    }

}

SDL_DestroyWindow( _window );
SDL_DestroyRenderer( _renderer );

/////////////
// SDL cleanup