Usually, my guild raids at a fairly steady pace.
People go AFK, assigning loot takes longer than killing the boss, and first-time explanations take anywhere from 10-30min (even though everyone is supposed to have read the strat and/or watched vids of the fight already).
PuGs (and some other guilds), however, are all business - the aim is to get the job done, not to socialize. Sometimes, I like doing these type of raids; they make a nice change to my guild runs, even though it can be a little boring with no-one to talk to.
Until last night, I didn't think my guild would ever really push for a speed run (at least, not in raids where some people still haven't killed all the bosses - Karazhan speed runs where people were on their 3rd alt don't count).
However, we did - and have Heroic: Arachnophobia, plus 3 wings of Naxx cleared in one night, to show for it.
I really hope we keep up the pace; it'd be nice to get to the point where we can clear everything (including Malygos and Sartharion) in our 3-day raid week before Ulduar comes in!