Bug Moving the mouse in play mode causes the editor to become unresponsive in 5.5.0xb5

Moving the mouse in the game view causes the entire editor to slow down and become unresponsive, until the movement stops. The CPU usage stays low, even while the editor lags.


I've attached a project where this can be tested:

1. Open the scene named "scene" and press play.
2. The view will start moving slowly after the mouse is moved, and the editor won't respond to any kind of input during the movement.

Edit: This only happens when the cursor is locked

 

After some more testing, it seems that reducing the mouse polling rate reduces the mouse lag as well. (It feels as if the mouse movements are being added to a queue rather than applied directly, and no other input is accepted until that "queue" is cleared.)

This doesn't happen when using the -no-thottle-updates command line argument, but it looks like that option was omitted from the latest build(s), so it looks like the only workaround now is to unlock the cursor.

 

Yeah, that's what the OS does. I guess what's happening is that only a portion of input events are getting pulled from the event queue during each editor "tick", and they're piling up faster than they're getting popped.