When you first log on to TB, all the threads with new responses are listed in bold. From what I can tell, this feature only lasts about 10 minutes before everything reverts back to plain text, and it becomes much more of a chore to see the new threads.
This is a lot faster than the other vBulletin boards I visit. Some of them have titles remain bold for a real long time, long after I'm done reading the board. I think this setting should be increased on TB to much longer than it is now. JMO.