Hey HeDa,
1. I just checked, when I turn of special tags, the issue is gone.
This is with special tags on. Notice the lag during playback and when locating the editor cursor:
https://www.dropbox.com/s/zs952xuv2q...20lag.gif?dl=0
2. I have to check again, before I give false answers, but as far as I noticed:
when I remove the tags from the current project, they are gone from projects that previously had tags. But I will have to check again and report back!