In a community based startup, what is a good community growth velocity? What is a worrying one?

I know this depends on the community in question, how actively I am marketing it, how well search engines have indexed it and so forth. But I was wondering if there are some good guidelines in terms of growth I could compare against to help me judge the growth of my community. I intend to use it to help determine where I should focus my time and energy. If the statistics for my community are healthy, I may focus more on coding. If they are worrying I'll focus more on growing the community.

How many visits, how many registered users, how many posts after time of community creation would be healthy, okay, worrying?

What sort of average per week growth is healthy, okay, worrying?

That's a tough question. Just for comparison though, my community at ConceptFeedback.com (where users can exchange website feedback) has been adding around 100 new members per week. Of course, some weeks have added a lot more, some weeks a lot less. We launched the site at the end of May 2009.

However, I think your focus should be less on numbers, and more on creating a great experience for each new user. At CF, we focused a little too much on "numbers" (get as many people as possible to reach critical mass - whatever that might be), while we should have been more concerned about investing in each new user, making sure they understood how to use the system and getting them "hooked". Here's a good article to that effect - http://www.kk.org/thetechnium/archives/2008/03/1000_true_fans.php Good luck!