I'm having trouble in windowed mode whereby I get occasional periods of frame skipping.
For example, if I turn on VSync and put a stopwatch in the OnRenderFrame() method, it starts off smooth (with 16.66.. ms per frame). However, after about 20-30 seconds I start getting 2ms followed by 30ms . It's very noticeable in the game. It's definitely not an issue with my computer not being able to cope, because if I turn Vsync off and don't limit the rate, I get > 1000 fps.
I tried the following: I turned VSync off, and used my own high-resolution timer (this uses winmm.dll for high resolution sleeping) to limit the OnRenderFrame() method. Doing this, the stopwatch now reports 16.66 ms consistently, however I can still SEE the frame skipping.
The issue goes away completely if I use fullscreen mode.