Whole game lags in PIE when holding any key - even unbound keys

Steps to reproduce (UE 4.26.2):

  1. Create a blank pawn.
  2. Add Floating Movement Component or alternatively create character and use CharacterMovement.
  3. Use the movement component to move your pawn forward constantly on tick by default (no need for user input) via AddInputVector.
  4. Bind Mouse to look movement via SetControlRotation.
  5. Play in editor.
  6. Move mouse around - no lag.
  7. While moving mouse hold any keyboard key, your choice, doesn’t have to be bound.
  8. Continue moving mouse erratically for at least 20 seconds(10 seconds for me), then slow down and see that input lags behind as the input queue is too long(or that’s how it feels).

Been struggling for days on this. Only happens when using movement components. Worse on CharacterMovement than FloatingMovement.

Finally today figured out it only happens when holding a key+moving mouse+using a movement component. Even when movement component gets vector added each tick by default, it won’t lag unless you’re holding a random key.

Gonna do the update slog now and see if 4.27.2 still does it.