> Delay rendering until just before VSync: If you get it slightly wrong and your frame takes slightly more time to render than you thought, your frame may not be done in time for VSync. Then it will have to wait a whole extra frame and the previous frame will be displayed twice, causing a hitch in any animations.

According to docs, there are extensions WGL_EXT_swap_control_tear/GLX_EXT_swap_control_tear [0], that cause late frames to tear instead of wait a full frame. They don't work on my machine (my Intel HD 4000 reports that it is supported and then silently fails), but this should be the ideal swap mechanism.

[0]: https://registry.khronos.org/OpenGL/extensions/EXT/GLX_EXT_s...