Totally wrong! More than 600k!
Excuse me, but are you bonkers?

On every page there are 15 posts, imagine that those posts are made by 15 different persons, all with a 600K siggy, that's 9 MB of data. Then imagine that 100 users watch that topic on that day and you are getting close to 1GB bandwidth for that topic that day. Ok some may argue that once you have seen the siggy it's in your cache, but some people like me clear their cache often in order to keep the system fresh. And if you are on a 500kb/s cable connection it will take close to 2.5 minutes to load that page.
All I'm saying is-get real!