I would recommend two things directed relating to your problems: one for the DM and one for you and your fellow players. And then one thing in general for the whole group.
For the players:
Make an effort to intentionally limit yourselves. Treat combat the same way you'd treat RP. Would your characters intentionally use their best, most powerful spells every time, immediately when they get in a fight? Or would they be more careful, knowing that you don't waste your best when it's not needed. Maybe in an hour you might get jumped by something much harder, and find yourself regretting expending everything on that bunch of mooks.
You can pretty easily make it an easy, very in-character sort of decision to not use your best, right away, all the time.
For the DM:
Mix it up a bit. One long, hard, boring combat every session means that players are always going to treat it as such, and react as such.
What if the DM actually made what I mentioned above happen? Give the players a fairly easy (but maybe not obviously easy, from the get-go) fight. Let them burn out their dailes and when the fight's over in fifteen, twenty minutes no big deal. Then, a short while later (and not an extended rest's worth of time) something bigger and badder ambushes you (maybe a nasty solo?).
This will help, on an in-game level, drive in the ideas mentioned above.
For the group:
Why is combat taking so long, and being so boring? 4e combat is *very* different from 3e combat. If you're having the same problems with it, then there may be some out of game issues coming up.
Are people having trouble with the rules? They're pretty easy, you might want to have them spend time making a quick re-read between games.
Are people goofing off during combat and slowing things down? Well, you can either try and ask them to stop (because they're making game less fun) or if it's a bigger problem and they really don't want the combat... don't do combat. If what the group really wants is RP and nobody really likes the combat part then tell the DM, and just don't do it. Don't include it in the adventure of whatever.
Hope that helps.