So I imported a CS5.5 project in the Premiere yesterday. It was a 40 minute sequence of 5D mark III footage. I worked on it around 10 hours and everything worked just fine.Then I rendered it, exited Premiere and went to sleep. Today I went into the project again. Everything works ok, besides playback. When I press space bar or play button it as normally transforms in the stop button, but the playback doesn't starts until after ~30s. Premiere doesn't freeze - I can still work, go in the menus, etc.. After playback actually starts it's almost as smooth as it was before. Scene change in the paused mode after moving cursor also requires a good amount of patience.
I tried creating a new project-importing older one inside. Also switching between Mercury/ No mercury
i7-2670, 8gb ram, 1GB nvidia GT-540M (I think), 120GB internal SSD, footage on an external usb 3.0 drive.
Please trash the preferences and clean the media cache. It might be the issue with the NVidia drivers. So, please go to the link provided below and update them as well.