glutIdleFunc() performance problem

Hi,

I have a problem with my project. If I activate glutIdleFunc() after several minutes I have a bad performance problem, slow framerate and I need to forced exit from the program.
I tried with a very simple idle func but I have always the same problem:

idle func:

void SelectionScene::animate()
{
time = glutGet(GLUT_ELAPSED_TIME);
timediff = time - timeprec;
timeprec = time;
const float ySpeed = 1.0f;

yRotation += ySpeed * timediff/14;	

if (yRotation > 360.0f) {
    yRotation -= 360.0f;
}

glutPostRedisplay();
}

main

void display();
void animate();
void reshape(int width, int height);
void mouseFunc(int,int,int,int);
void keyboardFunc(unsigned char, int, int);
void specialKeyboardFunc(int, int, int);
void changeScene();

//StartMenu start;
GameScene *game;
StartMenu *start;
SelectionScene *selection;
//GamePhase *game;
extern State CURRENTSTATE;

int main (int argc, char ** argv)
{
myWindow window1;
window1.init(argc, argv);

StartMenu s;
SelectionScene sl;
GameScene g;
Debug d;

start = &s;
selection = &sl;
game = &g;

// debug = &d;

/* switch (CURRENTSTATE) {
case STARTMENU:
{
cout << “yes” << endl;
StartMenu start;
game = &start;
break;
}
case SELECTION:
{
SelectionScene selection;
game = &selection;
break;
}
case GAME:
{
GameScene g;
game = &g;
break;
}
default:
exit(1);
}*/

glutReshapeFunc(reshape);
glutIdleFunc(animate);

window1.render(&display);
window1.mouse(&mouseFunc);
window1.keyboard(&keyboardFunc);
window1.specialKeyboard(&specialKeyboardFunc);
// game->setTime(glutGet(GLUT_ELAPSED_TIME));
//glutIdleFunc(animate);

glutMainLoop();

return 0;

}

void display()
{

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
glDisable(GL_CULL_FACE);

glLoadIdentity();

cout &lt;&lt; glGetString(GL_VENDOR) &lt;&lt; endl;
cout &lt;&lt; glGetString(GL_RENDERER) &lt;&lt; endl;
switch (CURRENTSTATE) {
    case STARTMENU:
        if(start-&gt;initialize()) {
            start-&gt;render();
        }
        break;
    case SELECTION:
        if(selection-&gt;initialize()) {
            selection-&gt;render();
        }
        break;
    case GAME:
        if(game-&gt;initialize()) {
            game-&gt;render();
        }
        break;
    default:
        exit(1);
}

/* if(game->initialize()) {
game->render();
}*/

glutSwapBuffers();

sleep(0.7);

}

void reshape(int width, int height)
{
switch (CURRENTSTATE) {
case STARTMENU:
start->reshape(width, height);
break;

    case SELECTION:
    {
        selection-&gt;reshape(width, height);
        break;
    }
    case GAME:
        game-&gt;reshape(width, height);
        break;
    case DEB:
       // debug-&gt;reshape(width, height);
        break;
    default:
        exit(1);
}

// game->reshape(width, height);
}

void animate()
{
switch (CURRENTSTATE) {
case SELECTION:
selection->animate();
break;
case GAME:
game->animate();
break;
case DEB:
// debug->animate();
break;
default:
break;
}

// sleep(1);
// game->animate();

}

How is this different from your other performance issue thread? Please,don’t open multiple threads for something like this!