In short no not really as it's one of the biggest sites.
Basing traffic on alexa (which isn't great but a good guide) Warez-BB is the biggest. You can check out
http://wrzc.org which lists sites by alexa traffic.
A thing to take into account is the number of topics as well as traffic. If a forum has hardly any topics but loads of traffic it stands to reason that your topic will get a greater percent of that traffic. You can order sites on wrzc.org by traffic by selecting "topics" from the sort menu.
Slightly offtopic but be careful reading "users online" as having coded them myself I know they are very poor indicators. Some have users online for the past 5 minutes, some for the past 10 minutes, some for an hour and some even for the last 24 hours. The other thing is how they are recorded via page loads, unique IP's and are bots like autoposters and googlebot recorded. I worked on a site were Google once crawled 500k pages in a day making the "users online" totally inaccurate.