There are many metrics that can be used in an MDA. One particularly interesting is the "Row count".
I use it to detect which SQL queries get more rows from a Database. While it might be fast on the SQL database side, and fast across the network, it normally has a big impact on memory usage from whoever is making these calls, as all this data has to go into memory...
What I select in MDA:
It's almost certain doing this will quickly reveal bad examples of database invocation. A quick example below shows some evident ones: