The timer feels way too long, especially as people get to know the cards better and don't have to read all of them.

I've gotten feedback on this in both directions; I'm going to try adding a "request more time" button.

When judging, seeing the timing of the cards coming out can skew the judgement, and also makes it easy to guess which card is the control.

The reasoning is that this gives players something to do while waiting for other players to put their cards in. The timing of the control is obfuscated somewhat - it puts its card in at a time uniformly at random from zero to the time limit, except that if all the humans have put their cards in, it shortens the wait to 0-5 seconds.