In our 4-viewport editor, I have noticed that when drawing objects the mouse movement gets extremely laggy. This only occurs when there is an event that causes all four viewports to be redrawn. It's not just four times slower, it's like an order of magnitude. It makes the editor unusable. If the event only causes a single viewport to be redrawn, everything runs at a normal speed.

Is there something special about switching contexts in OpenGL that I don't know about? Is this a known issue or something? I've never seen anything like this on Windows or Mac.