
Clearing messages for faster loading
If you frequently read groups with millions of headers, the large number of downloaded headers can affect Unison's performance. Clearing messages will remove the messages from Unison's database, while still maintaining an understanding of what you've seen. The next time you open a group, all of the new items posted since your last visit will load, without the overhead of Unison sorting through the old items as well.
To clear Unison's database for a group, choose Clear Messages from the Group menu.
Note: unlike marking messages as read, once a group's messages have been cleared, there is no way to retrieve the older messages without completely resetting your Unison cache.
Tip: Only use Clear Messages with extremely large groups. Most groups will not benefit from it.