Where exactly are you trying to export the video? where is the location of the files which you are using in the CS6 project?
Need a lot more info regarding this , as i am using CS6 , it works Great!!!
I skipped CS5.5, but I ran a test using CS5 and CS6 - same media file, same export settings, same hardware.
CS5 exported the file in 12 minutes. CS6 exported the same exact thing in less than 6 minuets, just over twice as fast.
I think I found my problem, my 2nd hard drive is starting to fail. After more testing using PPBM5, it started taking 3x times longer to export to MPEG2-DVD.
I just replaced the 2nd hard drive and now, CS6 is only a few seconds slower than CS5.5.
Close enough for me.