I was there last night. The traffic was a nightmare (rush hour). A taxi from Pearse Street to the venue took an hour so I ended up missing Tenacious D. Got to listen to the Ireland game on the radio though. The queue to get into the concert itself was also very long. Not too sure about the traffic afterwards as it took 45 minutes to queue for a ticket for the bus and then join a queue to get on the bus itself. It was all a bit of a shambles to be honest. You might have better luck on the M50 route though..