When I move the mouse over the window, the program runs much faster (cc. 3 times). This is a real time webcam .Net/Mono application running on a MacBook. On Windows works perfect. Is this maybe a power saving function of the laptop? The code:

Thread t = new Thread(Foo);
t.Priority = ThreadPriority.Highest; // I've tried without priority too, doesn't matter
t.Start();
...
void Foo()
{
    while (true)
    {
        ++k; 
        // then write k to the window somehow
    }
}