There was no clear visual feedback whenever a flashcard was loading on the review page, after it was upgraded to Ajax (see previous post).

In the case of network latency, it would appear as if nothing happened until the next card was loaded. I have fixed that and added a small 'loading' message.

PS: I am aware of a small annoyance currently in Mozilla Firefox: for some reason, you have to click once in the review page before the keyboard shortcuts work.