Dear Sweta,
As you said, above CRM datasource is appended with 30 fields and data has been populating through CMOD customer exit enhancement.
If the requirement demands us to do so, we need to go ahead with enhancement even there coming more filed.
Get some help from ABAPer and do performance tuning while writing LOGIC.
- Better SELECT statement first and get data into internal table. Then READ this table inside LOOP.
If really performance get worse, then go with generic datasource with Function module extraction(this is kind of extraction in BI, apart from standard SAP given datasources).
Best wishes,Vijay