Recommend me a GUI toolkit that is fast

[yoreei]

Hi! I recently started learning FLTK because I heard programs made with it were fast and light (as the name says). But I am wondering if there is an even faster/lighter alternative or is FLTK the fastest option?
Thank you in advance!

[Moschops]

Direct calls to the operating system API would be fastest.

[Cheraphy]

^I don't think direct OS API calls are technically a toolkit :P

[modoran]

There are wxwidgets, Qt, gtk+, choose one of them.

[HiteshVaghani1]

JUCE framework and Qt are best...