Make new "Members Online" behaviour optional (on befault).
Properly include the viewer into the list of users if they do not have the 'bypass privacy' permission
Note; converting the xf_session_activity table from MEMORY to InnoDB is likely a good idea if you want to use the Members Online query tuning. As MEMORY table has MyISAM locking behaviour, and this causes lock escalations when joins touch the a MEMORY table.
This update will stop listing normal users in the members online
The 'members online' sidebar fetches all active users (guests/robots/members) and does post-processing in php. This post-processing scales linearly as the number of users online increases. Including guests/robots!
This add-on now only shows staff and followed users who are online, while retaining the totals for the above categories.
A potentially breaking change is the list of members online (who are not staff or followed users) is now permanently empty. The full members online list is not affected by this change.