Strange timing, you might think. Why care about the old UI system now that the new one is available? Well, while the new UI system is intended to cover every in-game user interface situation you might want to throw at it, IMGUI is still used, particularly in one very important si...

In Unity 4.6 / 5.0, the generation of batches for rendering of the UI system is very slow. This is due to a few factors, but ultimately our deadlines kept us from dedicating the time to polishing this part of the UI, instead focusing on the usability and API side of things. ...