How to improve the reader to read more records per second in Transformations?

In transformations, Readers read at least 190 records per second until we upgraded ETL Tool Version:6.3.10.7. In transformations after upgrading, Readers could read up to 16 records per second maximum and they would take 2 hours to complete. If I used the same upsert logic in SQL scripts, those SQL scripts took ten to fifteen minutes to run.

We do not know anything about your transformation how it works and what you are trying to achieve but yet you want us to help you.

How????

There are multiple factors which have an impact on performance.
One of them is the performance of the source database.
If you have very complex SQL it might take a while for the server to return the data.
The easiest way to test it is to remove all transformations and write data into the text file.
Running the transformation will give you an idea of how fast the source SQL is
You can always try adding indexes or rewriting source SQL

The next thing is the transformations.
The more complex transformation the slower it is
Some of the transformations are very slow by design for example SQL lookup

Writing data can be very slow as well
Please read the following article
www.etl-tools.com/wiki/knowledgebase/issues/update-is-slow/

I hope you will find my suggestion useful