Last one I did in about 20 minutes was 8 orc minions lvl4 , 3 orc beserkers lvl 5, 3 orc soldiers lvl 4, and an orc shaman lvl 4. Most party members are between 3rd-5th, with 7 characters. Only 2 of the party members had a dance with death.
Once initiative is established, we roll through it quickly, I do the count, if the player is not ready with his/her power, we skip them and move onto the lower initiative count. If they can fumble through what they want to do by the end of the round, we let them. If not, they just lost their action! If I can group players actions, I do. So three players come up in the initiative count and they are all against different monsters, I have them all roll their hits and damage. While they are doing that, I am determining what the next person/monster in the count is doing. Generally speaking, we might have three-four resolutions of powers/attacks going on at once.
Myself and another player are the 'movers' for the combat grid (if we use it). Meaning if player a says I want to attack this guy, we quickly take his movement, and tell him what effect, negative or positive the move will generate. If the player still wants it moved, we move it. Players like to an inordinate amount of time if they are moving the pieces themselves. If the players is good and fast at it, we generally let them do it. This speeds up grid combat.
Sometimes to speed up grid combat even more, I just have a lot smaller version of the map behind my screen. I make pencil marks where everybody is at, and move them as I would my own character for the action the player wants done. If questions arise, I can quickly show them the map, the route, and why. If they want to change it, that is fine. It is still a lot faster!
That is how we get through combats faster.