Timeline unnecessarily populates email_map from all known users
|Reported by:||Owned by:||Remy Blank|
env.get_known_users is an extremely expensive query if you have many sessions and attributes. The timeline uses it to populate a user name→email map for RSS author emails. This map is populated even if format != 'rss'.
Simply wrapping the email_map construction with an rss format check gives a large speedup for normal timeline use.
In the future, the user schema should extracted from the session or at least cached in-process.