[MENTION=65726]Mengu[/MENTION] - Great explanation of how a Paragon turn can wind up taking a lot longer.
I played a Paragon level campaign using a Dragonborn Sorcerer with the Dragonfear option. I also went with a lot of blasty powers, since most of the rest of the party was single target or used Burst 1 attacks (Bard, Monk, Warlock, Barbarian and Fighter).
So, a typical turn for me took a long time, but not due to be being unprepared. In fact, I was probably the most tactical player in the group, and would usually be developing plans literally as soon as my turn was over. But when you minor Dragonfear, which basically hit the entire encounter, and then use your regular action to do a Close Blast 3 or 5 on 3+ enemies, and then Action Point to do it again, things take awhile. Even rolling against multiple targets at once (I had 4 dice sets, which is all I could really easily manage) along with with the damage dice only helps so much. If your Dragonfear hits 8 guys, who all have different defenses, it takes awhile to calculate.
And then once you do figure out who that hit, you have to take into account on the subsequent attacks that now some of the guys are granting Combat Advantage from Dragonfear (as well as somehow marking the ones you hit so that everyone knows they're granting CA, have a -2 to hit and are marked). So even though I use CB and power cards, I still have some extra math to do (or the DM, depending) to take into account the additional mods from status effects. And then do that twice, because I used an Action Point.
Contrast that with our Bard, who typically just used Jinx Shot every round: "*Rolls for Jinx Shot* Ah, I missed. Anyone need heals? No? Okay, that's it for me." He never really planned his turn out ahead, but because he basically just spammed his At-Wills and rarely used Encounter or Daily powers (don't ask me why...), his turn still went pretty fast. But you can't always just make universal judgements about how fast something should be as players get more and more powers, because there can be vast differences between even how optimized characters will play out, just because of the nature of what they are capable of doing in a turn.