i found that my "slow channel changing" problem is fixed by constantly deleting all log-files in the tv server log directory. i wasn't able to turn off logging so i created a windows task (-> execute a batch file to purge logs every minute). after purging the channel changes within 2 seconds. with logs present it takes up to 19 seconds (when watching tv as well as during the Test Channels in the configuration).
i'm using the mepo 1.2.0 RC on win 7 x64 - hope this helps anyone