I experience this constantly with Cache SQL. Especially when querying the ATNA log.
SELECT TOP 400000 * FROM HS_IHE_ATNA_Repository.Aggregation ORDER BY ID DESC
That took 12 seconds. I then upped the number to 500,000 and it took 185 seconds.
Shouldn't the execution time scale proportionately?
If I run the 500,00 query again it takes 2.4 seconds.