Do consolidated tracks playback slower than edits?

[michaux]

I have been working on a particular song for some time making many edits and increasing the number of audio files accessed by this song. The playback has not been particularly sluggish at all. I am about to get the song mastered as part of a complete record and making backups, dumping unused audio, etc, etc. I saved as another name before removing unused audio and playlists. I did not permanently delete any audio files but only removed them from the session. I then consolidated all edits and compacted the consolidated tracks. This normally makes playback more responsive with no apparent latency. This time, it had the opposite effect. My newly purged, consolidated & compacted session runs extremely slow. Screen redraws are at a crawl pace. Metering is useless and mouse moves within the session are impossible. What could have caused this?