I can confirm (and have captured video) this issue - I can reproduce this 100% of the time.
- Xbox One controller connected via Bluetooth: FPS takes massive hit, maybe 25% or less of normal performance.
- Xbox One controller connected via USB: Works without issue
- No Xbox controller (just Keyboard/Mouse): Works without issue
I took a quick video, when I had the controller connected via Bluetooth - this is running in ‘high’ at 1440p, the FPS drops to 30fps and even lower, with severe stuttering. Mid video I take the batteries out of the Xbox One controller (you see the controller prompt for a split second), and my FPS returns to it’s normal ~110fps with no stutters:
(Can’t post URL links - it’s a video on streamable, streamable-dot-com/91g4hm)