Then of course it is a good oportunity to discuss. I was afraid that we are gathering resources for "great BOOST U++ comparison article" which is a bit scary idea to me.
As for U++ widgets being faster... Well, first of all, I am not quite sure they are necessary faster
Easier to use, producing more compact and easier to maintain code for large apps, that is the design goal.
But of course, we are trying hard to be fast too. Concerning widgets, the most impact has effective repainting.
Also worth noting is that regular U++ widgets are not implemented as host platform widgets - in other words, for host platform it looks like U++ window is covered by single big widget. That might make things less resource intensive as well (sizeof(Ctrl) is now around 100 bytes, that are all resources needed for widget to exist).