Rudder+brakes=fps loss

[Bilbosmeggins 217]

Hi all. After a flight, last night, I was taxiing back to a parking bay to end the session when I noticed an odd thing. The world was rolling by fairly smoothly until I applied rudder and toe brake to turn. Immediately, everything became jerky, like the frame rate had halved or something. So I spent the next 5 minutes or so trundling around the airport to see whether it was a one-off, or not. It wasn’t. It was absolutely consistent.
 

The effect was the same both sides of the cockpit. In other words the inside, or the outside of the turn with the scenery having to slide by faster or slower, if that makes any sense.  I’m using MFG Crosswind rudder pedals, and have never considered them to be a systems hog. Is it just my rig, or is this a common thing?