I think it's not so much doing things slowly that gives the impression of confidence (or seductiveness, I suppose?), it's doing things deliberately and with purpose. Doing things slowly only underscores the emotion behind the action.
Think about it. Without that element of deliberateness, doing things slow might look like you're a little slow... or possibly geriatric. Or baked out of your bean.
how lovely... :love:my girlfriend said:Let's take it slow