Huge performance hit UNLESS RenderDoc is running?

Okay, so been developing a native engine port to Quest and Quest2 that's been running absolutely fine for months until the latest MobileSDK update and/or headset updates (it's been on the shelf a month and getting back into it). Now the app runs horribly slow on both Quest and Quest 2 so I hook up RenderDoc and it blasts away flawlessly on both headsets. WTF? Turn off RenderDoc and performance is horrible again, turn it on and it's fine. What am I missing? Is there a debug setting somewhere that's looking for the RenderDoc server or something? Help please!