Issue: fetch_activity_list does not scale

I only have 2600 issues in one project, but as admin the timeline function fetch_activity_list creates a temporary table and and sorts all the rows. Out of all the queries on the project page, it takes the longest (roughly 99% of MySQL time on that page, at .17s). I have thought of a possible improvement on this query, by separating it into two queries. If it works as I expect I will commit the changes.