Add me to the list on this. I've been ripping my hair out over this for 18 hours.
I had two 8GB sticks of Corsair Vengeance LED RAM (installed October 2018), and then I decided this week to add two more of the same model to get 32GB of RAM.
After installing the extra RAM, I wanted to sync up the lighting of them so I downloaded the iCue app. It's been a couple days, so I forgot all about iCue being updated.
Next time I booted up a game I noticed I was getting sluggish gameplay, so I assumed maybe it was an issue with the new RAM, or maybe my MOBO/CPU doesn't like 4 sticks. But then no matter what configuration of RAM I put in my MOBO I saw no difference.
I've run a million tests, uninstalled and reinstalled a ton of drivers. I even tried putting games at the lowest graphics settings and still saw poor performance. And when I was ready to give up and reinstall windows my buddy found this thread. Reinstalled the older iCue app, rebooted my computer, and now all is well.
I'm running a 2080 TI, 32GB of RAM, 8800k, that level of performance was on par with my 970, 8GB of RAM, and a 2500k.