Currently the Activity Stream by default will query every single issue in JIRA and then order by those results. For larger instances, the timeout of 10 seconds is not sufficient for this query and will often result in the stream timing out.
JIRA 5.2.9 - 5.2.0 stream
Mac OS X 10.7.5
Specs of instance verified with:
Load up a decent sized JIRA instance and access the activity stream.
The stream doesn't time out.
The stream times out sporadically.
This appears to be due to the Activity Stream querying for all issues from projects browsable by the current user. They are then sorted by updated date and the stream will only display 5-10 results. A suggested easy fix would be to only return issues from the past month as this would significantly reduce the amount of issues returned by the query.
We have a KB with suggested workarounds - please see JIRA Activity Stream returns One or more activity sources were slow to respond and are not included for further info.