I have been using the MBR for a few days now with no issues and no UI lag but today I tried mirroring to ATV3 and was very choppy. My Atv was set to auto (1080P) i changed setting to 720 and it was better. Atv is on ethernet and MBR is on 5ghz. I tried video from several sources. Video was smooth on MBR but choppy on Atv.video