When clicking into a forum which is noted to have new posts since the last visit (as indicated by the yellowness), the red text which used to be to the right of the thread title showing the number of new posts, is not there anymore. I'm using Firefox, but seems to not be a browser-specific issue.
I had to disable that feature as it appears to be the cause or at least related to the recent performance issues. Since I'm not sure which yet, I don't know if it's something that can be reworked or if it has to be scrapped completely.
I'll post something as soon as I know. But, I won't have time to take a closer look until next week. Between the surprise [ha!] birthday party that my wife is throwing me tomorrow and other commitments time is very tight this week.