Last night I installed RC2 of LR 4.1 and it started to overload my CUP (up to 600% on activity monitor) at the task of generating the preview on second display. Up to LR 4.1 RC1 everything was OK here, now during auto-import photo shoot the second screen does have a problem with preview rendering (no preview is generated well - it simply stretches the small preview with bad quality and the CPU gets overload by far at the same time). My iMac got very hot after some 10 minutes or LR 4.1 RC2 work and I had to quit the LR and revert back to RC1. Prior to going back to RC1 I reproduced the RC2 CPU overload immediately once again after complete shutdown and restart of the system so it was not a single isolated case. I had such a problem for the first time ever - I work with Lightroom everyday since version 1.
Please address this bug in final release, and if necessary I can give more details.
My hardware/Software config:
iMac 27 i7CPU mid 2010 + CinemaDisplay 27, OS X Lion 10.7.3 with all latest updates, Adobe CS 5.5 + Photoshop 6 public beta, camera working via AutoImport of Lightroom (Canon WFT E-2 connected to EOS 1DsIII working in FTP mode).