Emmanuel

That is a big question and it depends on what you are doing.

If you are writing SQL queries, then look at the SQL performance statistics in INFORMATION_SCHEMA.STATEMENT_DAILY_STATS. 

If you are using an interoperability production, look at the activity and volume statistics.

For general database activity, you could use ^SystemPerformance as described, but with that you have to process the data with an extra tool and it is difficult to interpret. I suggest you enable the History Monitor. It will give you almost everything ^SystemPerformance gives you, with a fraction of the effort. You just look at the DB and CPU stats with SQL.

That works perfectly with the caveat that a restart was needed for the messages to appear.

Thanks.