I'm unsure what could be happening there. We did change how we do some parsing and replacements of our tags in the 6.2 release, which has had a very positive performance improvement. We haven't heard of many issues with the change, but it's likely the cause of what you're seeing.
Looking at the output of the HTML, I don't see anything obvious with the plugin disabled though. Can you PM me admin credentials for your site so that I can enable the plugin and test what happens then? We'll gladly do whatever we can to get you going.
You can PM me by clicking the mail icon under my name to my left.
Thanks,
Alex