Membership Contribution Details reports chokes due to unindexed join

The Membership Contribution Details report's "statistics" SQL chokes on modest data sets because the temporary table created by the report is unindexed. With a temporary table with 56K records, I had to kill my MySQL query after 10 minutes with no luck. Indexing the temporary table added .3 seconds to the insert, and the statistics computed in a fraction of a second.