How does Polonius’s reaction to the player’s speech provide comic relief?

Polonius is presented as a faintly absurd figure in Hamlet and often provides comic relief, whether intentional or not. One such example comes in act 2, scene 2, when Hamlet requests that the lead player of the acting troupe perform a speech from Virgil's Aeneid detailing the death of the Trojan king Priam and his wife Hecuba's grief-stricken reaction. The actor does as he is bid and starts giving a long, passionate recitation of the speech in which he skillfully displays a convincing degree of emotion.
But the speech is way too long for Polonius. He's thoroughly bored by the whole business. When he introduced the actors to Hamlet, he told him they were the best actors in the world. Yet now he's finding it more than a little difficult to maintain interest as the speech drags on. Earlier on, Hamlet himself had had a go at reciting the speech, and the ever obsequious Polonius offered him fulsome praise in response. But when it comes to the actor's turn to speak, Polonius unhelpfully interjects with his own running commentary.
Much of the humor in this scene is ironic. Polonius is notorious for his long-winded loquacity, never using a single word where several will do. Yet in the figure of the lead player he's encountered someone who can talk even longer than he and, what's more, with apparently genuine emotion. All this somewhat unnerves Polonius, which merely adds to the humor of the situation.