Dear Tony

Thank you very much for your analysis.
Those are my answers for each TCode

Ztest1

That's a good point. How do you plan to split the VBAK fetch?
If you are thinking about changing the JOIN by individual select statements, try to avoid using FOR ALL ENTRIES as this will cause a huge traffic from SAP server to database server.
For your info, as FOR ALL ENTRIES is not a native SQL statement, this is translated by SAP into several select's, one per value found in the internal table used in the FOR ALL ENTRIES. As a result, we will have thousands of selects and the results are put together before returning to the program flow resulting in a high time consuming execution.

Please, go on with the enhance for this VBAK fetch but be very carefully.

Ztest2

It's quite surprising that the BADI will be slower than a BDC.... I have a question here..... only 2 fields are being modified in all cases or it's different depending on selection screen? What's the execution time if we change more fields?

Ztest3

It's difficult to say as there is no special fetch consuming too much time....
Please, ask key user, which are the most common selection criteria used by the users

Thanks for your job

Best regards

Tom