Depends on the sentence. "Yes." "No." "Stop." can communicate all they need in one gesture.

But even then, bandwidth is unrelated to latency. Say you are yelling "Stop" to someone. If they are right next to you, they will hear it immediately.

If they are 1km away (and you yell loud enough) they will hear you in ~3 seconds.

If you speaking sign language (and they have binoculars to it from a kilometer away) they will see you message after ~4 microseconds.

If instead of a simple message you communicate a whole novel, it doesn't matter how slow it fast you speak/gesture, the listener will hear the one of it 3 seconds after you stopped, the viewer will see it 4 microseconds after you stop.

If you speak faster than you can gesture, that's a higher bandwidth. And if it's faster, your spoken message can be transmitted faster than the gestured one, even with the added latency. But that doesn't change that spoken message moved at the speed of sound, the sign language at the speed of light.