Right now, we wait 10 frames worth of vsyncs to disable vsync. This is pretty short and there are lots of instances where we disable vsync quite often. For example, even a blinking text carat can enable/disable vsync (http://mzl.la/1H2Sdpx). On OS X, enabling/disabling is a non-free operation (see bug 1138502) because the OS creates a new thread every time we enable vsync. Let's wait a bit longer than 10 frames to re-enable / disable vsync.