When I used USB keyboards with my tablets in host mode, there was a lag when typing, and I just noticed someone else reporting this in a thread about bluetooth keyboard lag.

Has anyone else seen lag when typing on a tablet with a USB keyboard?

If this is a common problem, it could be that the text input system itself is unable to cope with very fast typing speeds. (And that would make sense as it was originally designed just for the on-screen keyboard where typing speeds are slower.)

It would also explain the Bluetooth keyboard lag which many have reported.

If this is a widely-observed problem, I'll try to add this to bugzilla. I know USB keyboards aren't officially supported, but BT keyboards are, and the cause of both lags may be the same.