I got tired of a bit slow combat in 4e and when my players made their characters for the current campaign, I asked them to put most of the power in offense, not defense. I am running Reavers of Harkenworld and the encounters that are equal in level are mostly over in 3 rounds. I had one encounter that was done in 2 rounds (without spending any dailies).That's contrary to my experience - 4e combats can get very involved, 3 rounds would be awfully short. Not that it can't happen, given, say, an optimized or striker-heavy party and a less than complex/tough encounter, just that it's not the norm. And, rounds can take a bit longer in 4e because all PC turns potentially take comparable amounts of time to resolve, which generally means casters taking maybe a little less time, but martial ones potentially noticeably more. But, mostly the difference is that 4e combats go more rounds, because everyone has more hps relative to the damage being put out - they're designed to be longer, so tactics can be brought to fruition, and combats kept 'dynamic.' Really, because, just as 5e is over-reacting to complaints about 4e being slow, 4e was over-reacting to complaints about 3e being 'static' and 'boring.'
Often, it seems, the game just doesn't need as much grease as the squeaky wheels among it's fans demand.
I have got a paladin/sorcerer hybrid, a brutal rogue, a druid and a bard. At level 1 the Rogue does 1d8+5+2d6+2 on a at-will attack, and can add 1d8 once per ecounter (half-orc racial), and do 1d8 extra with his encounter power. He usually uses his encounter power with the racial for 3d8+5+2d6+2 = 12 - 43 = 27 damage. The Paladin/Sorc does 1d8+8 in a close burst 3. Pretty neat