Weird Network Anomaly

I have a dual-band wireless router. I have a Macbook Air connected to the 5 ghz band. Network Utility shows 300mbps on the connection. I have a 3rd generation Apple TV, also on the same band. Airplay Mirroring from the laptop to the Apple TV is horrible. It stutters if it launches at all. However, if I switch the Macbook Air to the 2.4ghz connection, it works great. It's not particularly a problem, I'm just a bit anal. Any ideas why this could be?