Yeah I really want to see the numbers on this.
It seems to be a absolute breaking issue for them, suggesting a actual noticeable delay. So it should at least be one frame (on 60hz display) of additional latency compared to x11. Especially since there is earlier work Using a Click based measurement setup showing no such delay.
The pi is either emitting a mouse move or detecting one on the physical device and measuring the time that passes until the photo diode/resistor (not an led) is detecting the cursor to move away.
It’s essentially the same setup you would use to detect input to photon latency if you don’t have a high speed camera.
Edit: Ah no there’s another setup with a pi pico in there… Yeah it’s binding and LED Lighting up to a button press to have two visual indicators (LED and Cursor Reaction) you can measure using a high speed camera. Them only having a 90fps phone camera makes it means the measurements are only in 11ms increments though.
It does, in fact the current version of the wine patch is incompatible with fsync and esync, at least in wine-tkg. Which makes sense since it supersedes both (does the same thing in a more correct and more performant way).
Starting with denying her person-hood under the unsubstantiated rumor she is the alter ego of marcan, found in this very thread.