Yeah, I'm with you on that.
When you say you "keep the dial set to 10 on intensity, so the players WANT to move fast", can you elaborate? For example, I ran a very dangerous, complex, "intense" boss fight that took about 6 hours all told, with several players were taking a long time despite the dramatic tension. Are you doing something I'm not?
No, and I agree that when you get to really complex fights they can still take a long time, and then there's no way to sustain that level of energy. These days I tend to break them up, so I might have the equivalent be a few shorter encounters, some chase/escape/problem solving sequence (with pressure), and then another shorter final encounter, say perhaps the 'final stage' of the boss that might have been fought earlier. That can create a more interesting and dynamic pacing. Some of it is atmospherics too. I always inject some level of time pressure or some goal that is just within reach, intense rivalries, that sort of thing. Then it falls down to dramatic description, maybe some props, etc. Just something so that the players are hooked, they want to be carried along and see what comes next, much like an adventure movie. Nobody would willingly stop the VCR at the point where Indie is about to jump on the truck and try to recover the Ark to take a break. Likewise if the the whole mine is about to collapse most players can be convinced to hurry up and do their turn and see what happens next.
I do try to go over player's sheets with them now and then as well, give them some tips, encourage them to come up with their next round's moves ahead of time, etc. I also do the monster turns very fast. Sometimes I miss an opportunity or forget about some capability some monster has, but oh well. I can generally run 8 monsters at about the same speed as a player can run one PC, so my turns are 20% of the whole (another reason to for instance break up a multi-stage boss monster into a couple encounters, keep each one simple, this is also a good argument for staged bosses in general as each stage is separate and simpler).
What I find is that when my 'velocity' is high, the action is highly intense, the monster's are rolling out their turns bang bang bang, then the players often will get into that flow too. The thorn in that is always that one player, but IMHO generally if you work out a shtick with that guy's character, so you get together and crib a little "OK, do this early on, then do this a lot, and if things get really hot, then unleash THIS" they will at least usually get somewhat faster. Nothing is perfect, but honestly the same player that is the slowest in my 4e games, was just as slow playing a rogue in 2e, and is equally slow in my sister's 3.5 game. Its not as critical in 2e, but still, nothing will make that player FAST.
