Render the GUI and screens at a lower framerate to speed up what's really important: the worldrendering.
Renders the GUI at a lower fixed framerate (configurable in the settings), freeing up CPU and GPU time for the world rendering. There is no good reason to render the hotbar at 100+ FPS.
This is still work in progress software! There will be visual issues/compatibility issues with other mods! Also currently in maintenance mode. No new features will be added or bugs with other mods fixed!
No.
Try it and see. Keep in mind, only the Vanilla Gui is supported, don't ask about mods that replace stuff in the UI.
No backports are planned. Mainly due to engine limitations in older versions.