Both require an insubstantial amount of time. Call it a fraction of a second if you want. You only get one swift action per round, free actions are unlimited unless stated otherwise or within reasonable limits decided on by the DM (speaking is a free action, but you can't recite a sonnet in one round, for example). Swift actions are always during your turn, though immediate actions (related to swift and count as your swift action for the turn if you use it) can be used when it's not your turn to act. Free actions are limited to your turn unless specifically stated otherwise, iirc.
I'm, however, pretty sure they're notI'm pretty sure immediate actions are the biggest culprit for slowing combat down.
Considering that that a character with immediate actions available could need to be given the time to interruptI'm, however, pretty sure they're not![]()
You already mention why it's usually not a problem: not every character even has something they can use as an immediate action. And for those that do, it's typically a limited choice. And why would I want to reserve the time at every conceivable 'interrupt point'?Considering that that a character with immediate actions available could need to be given the time to interrupt[...]