Why does IBM DMC is heavy on production Db Server in terms of memory utilization? Monitoring tool should not consume so much memory. 

It all depends on what you have configured in your monitoring profile, and how busy is your database.

For example, if your database has a lot of tables and indexes, you might want to disable the storage data collection:

If your database is very busy, you can also increase the collection interval.

Keep in mind that for DMC, it does not matter how big the database is, what matters is how busy they are.

If you have a database which is not so busy like a Data warehouse database, running few applications, the performance data collected will be a lot less compared to a very busy OLTP database running hundreds of applications.

DMC needs to collect data for everything that is running on the database.

I am not sure if you have the event monitors turned on or not.  But if you turned on the event monitors, specially the activity event monitor, you will have the overhead of the event monitors on the database.

In summary, the recommendation is to analyze your environment and what you want to accomplish using DMC when you have a problem.

Here are some points:

• For example, turning on Activity Event monitor for a database running thousands of queries for second, when you have a performance issue, do you really need to see all the small queries running on your system, or just the problematic ones?   DMC captures the problematic ones using Db2 table functions, not activity event monitors.
• If your database is too busy, and there is no performance issues, increasing the monitoring interval from 5 minutes to 15 minutes from example, it might help decreasing the data being captured.

I hope that helps!