[pecinko]

Don't know if it is known or not but:

If I run XBMC on secondary display there is noticeable performance drop. If I make external display my main screen from System Preferences everything gets back to "normal".

MBP 15" & ext 1080p@60Hz LCD on XBMC RC2

[Ned Scott]

Specs on the MBP? Especially the GPU(s).

[pecinko]

Well, not the fastest one

2.66 Core 2 Duo, 8GB, 9400M 256MB, OS X 10.7.3