To speed things up in my 4e game, I'm thinking about ditching the cards and instead giving my players power sheets with checkboxes.So dramatic improvement in the speed of combat, at least for our group. I think it's because I've provided power cards for everyone, the wizard/cleric also don't spend too long deciding what they are going to do, which was a problem in 3rd Ed.
EDIT: oops. That last poll option should read "20 or more."
Typically 2-3 per session.
We're playing 3.5/Pathfinder and normally game for 5-6 hours a session. Games are RP focussed and tend to involve a few bigger climatic battles rather than many smaller encounters.