Side buttons on mouse not working if iCUE is turned off after latest firmware update

I've got a weird problem. Right now I have a Corsair Harpoon RGP 0030, and when I opened iCUE a while back, I got a notification about there being a firmware update for it. So I updated the firmware. Now the two side buttons won't work unless I have iCUE running, and iCUE itself gobbles up system resources like it owned the place (it's not uncommon to see it take up 50% of my processor power for no apparent reason, and Corsair services will gladly eat 600mb of RAM).

I don't have any other corsair products than this mouse, there's nothing else iCUE should be interacting with.

*edit*

Seems like iCUE basically claims the first core, Core 0, as its own once it's been running for a while. Not what this thread is about, it's about the side buttons, but reading the forum, I see that plenty of other people are reporting a similar issue, so something is fishy about iCUE.