Weird. The hbmenu 3dsx I have loads instantly without the icon-loading routine (flashing glitchyness).
I guess newer hbmenu binaries have a modified title selector function that loads the icons this way. But why doesn't the one I have do this?
Edit: it's used to know what the ropbin is doing currently. So if it freezes on some color, someone could track back the cause of the freeze. Also, if you have a list of so-called "gadgets", that you dumped from the 3DS's software, you could edit the ropbin to not flash the bottom screen.