SeAccessCheckWithHint

If you're using Process Explorer to grab stack traces in order to narrow down what has gone insanely slow/wrong, and every stack trace bottoms out at SeAccessCheckWithHint (below things like PushLock, SpinLock, WaitFor, and Synchronize), it is NOT the case that your thread is just spinning.  Rather, this is the only time that Windows can jump in to grab the stack.  Look higher!