It really depends on your players / group. I played a Malconvoker and my turn (including creeps) took about a minute.
DM: Kasz, you're up
Me: Okay, Spider 1 vs Orc 4, AC 13, 16 and 4.
DM: Miss, Hit, Miss
Me: right 20 damage, Fort Save DC 17
DM: Pass.
Me: Okay, Spider 2 vs Warg, AC 18, 9 and vs Goblin Rider 14.
DM: Hit, Miss, Miss
Me: right 22 damage, Fort Save DC 17
DM: Fail
Me: He takes 4 Con. With my turn I move here and cast Solid Fog. *Scribble on map.*
Next game rolls around and a friend decided summons were cool... cue
Frnd: Right, well I summon... oh... hmmm... Can I summon a shark on land?
DM: Nope
Frnd: hmmmmmm, I summon.... ummmm.... a Gorilla
Gorilla's turn: I move it to hit Orc 1
DM: Hitting what AC?
Frnd: Well I rolled a 16
DM: Modifier?
Frnd: dunno
Table: Facepalm.
Leaving us with a houserule of, if you don't know, you don't get. That friend is particularily annoying though... given 2 months to prep he turns up and writes the character sheet during the session... so when prompted to make saves etc... he just didn't know what his mods were... highlight being
DM: "Okay so you're all in the corridor."
Frnd: "Wait, I took 36 damage in the room ten minutes ago right?"
DM: "Yeah, I think so"
Frnd: "Right, I've just rolled my health and I'm unconscious and bleeding out"
Table:
I've got no problem with you wheeling round a small army... but if you can't take your turn quickly you're always going to cause upsets... The Cleric that takes 2 minutes to take his turn controlling 4 zombies, a undead leadership and his character is always going to be more welcome than the Wizard who forgot to write down his familiars stats.