Our LiveReport was taking a long time to run, so I've made a very simple amendment to the SQL to improve it:
select DTree.*, DVersData.MimeType, DVersData.DataSize from DTree with (Nolock), DVersData with (Nolock) where %1 and DTree.DataID=DVersData.DocID and %2 and DVersData.DataSize > 1000000 order by DVersData.DataSize desc
This means that it ignores the millions of documents that are smaller than about 1MB.