I'm using a Logitech G903 and I do have Logitech G HUB installed and running but I've already tested this with G HUB enabled/disabled with iCue enabled but that didn't stop the stutters.
No other game suffers from this issue, and I have turned off the SDK to try and see if that would help, it didn't :( Also I've got a Ryzen 2700X with 8 cores and 16 threads, I doubt iCue alone could bog it down that much. I mean I can even game whilst transcoding videos to x265 and FPS drop is noticeable but not too severe.
My GSYNC is already on Fullscreen only and I play in exclusive fullscreen mode everytime (unless the game doesn't support it)