I was going to post this same issue.
When I first load a plane now that uses Gizmo (including the G500 on non X-Aviation planes) I get a huge cpu draw from Gizmo. My cpu frame time goes from 0.200 to 1.500 for a minute or so.
Eventually it settles down and Gizmo shows about 0.10% usage in the admin window. But then every minute or two it goes back up to 50% usage for a few seconds before settling back down which causes stutters.
I've tried this with the 737, Mu2, BN-2T and the Laminar 172 with G500.
I bought both the 737 and the G500 at the same time so not sure which one triggered it.
My system is old, i7 4790 and I have a 5800X3D build I'm completing tomorrow so I'll report back if it continues with that new system.
Prior to this week I never had an issue with Gizmo so did something update it on the 737 or G500 purchases?
Btw my tests were done at various locations including Land's End which is usually very light (I get 60fps in the stock 172) just to rule out scenery problems.