"The right word may be effective, but no word was ever as effective as a rightly timed pause". - Mark Twain.
It can nerve-wracking to stand on a stage and look at an audience, while they're looking at you, and no-body is saying anything. It will feel downright weird, and possibly quite scary, if you're not used to it.
But a good long pause at the right moment of your speech can hugely enhance your performance and impact. A pause will: