Swift casting Polymorph on a Paladin is pretty strong, imo. They already benefit a ton from having ridiculous Str. Combining that with the ability to dump Str at the start... Well, its very strong.
Swift casting of Evard', to keep mobs away, swift solid fog, swift haste, swift mirror image (at relatively low levels), swift True Strike(!!!NO NEED FOR SHOCKTROOPER ANYMORE, WITH ONE FEAT!!!), etc etc...
It takes a Wizard in 3.5 a lot of levels of some specific PrCs and feats to reduce Quicken spell by that much.