Activity Feed: Requirements and Load

A developer community has 3 million members, and about 430,000 of them sign in on a typical day. Every day they publish about 1.3 million activities: posts, answers, comments, stars on projects, and project releases. Each member sees an activity feed, which is a list of recent activities from the people, projects, and tags that member follows.

Averaged over a day, that is about 15 new activities a second and about 30 feed opens a second. Neither number looks large