Mystiq.org - forum: GCD u totemu -> Shaman -> Bugreport

The global cooldown is generally 1.5 seconds for all classes except rogues, Cat Form druids, and death knights in Unholy Presence, whose abilities are mostly one second global cooldown. Shaman totems also only trigger a one second global cooldown as well as warlock curses with Amplify Curse . The global cooldown affects the wait for the next ability, so using an item or ability with the standard 1.5 second cooldown will require waiting that long before a 1 second global cooldown ability can be used.

Totems only trigger a 1 second GCD as opposed to the regular 1.5 second GCD. Totems are also considered Physical spell school so they can be dropped even when silenced.