Scrolling worked fine in the old launcher, but is really slow in the new launcher. By scrolling, I mean that if a player has a lot of worlds, or servers saved in the launcher, and they try to scroll with the scroll wheel, it is very slow.
I have checked that this is not a problem with my mouse or my computer. I tried the old launcher and scrolling works fine in there. I also posted this on /r/minecraft and others were also experiencing this problem.