Back after some investigation. I present findings in case anyone else can use them and in case someone can point me where to head from here: I was planning to start creating new custom record types to experiment with the "Date_Last_Modified" field, but I thought I'd start off with first examining the behavior of existing tables. I dumped the definition of the standard records, and was surprised to find that there didn't seem to be any index on any "date*" field. Figuring that maybe they are hiding this info for some reason I tried simply querying to check behavior. I queried against the standard "Customers" table, which conveniently had the same number of rows as the Profiles table. After experimenting with querying and sorting based on the "Date_Last_Modified", I'm pretty confident in saying that there is no index in use. Regardless of WHERE conditions or ordering, the query takes 10~50 seconds grouped strongly around 30 seconds.