I am working on an ABAP program that reads and processes a large amount of data from database tables and internal tables. The report is taking a long time to execute, especially when the data volume increases.

The current program contains multiple SELECT statements inside loops, nested loops, and repeated reads on standard internal tables. It works for small data volumes, but performance becomes very slow in production.

I would like to understand the best practices for improving ABAP performance when working with large internal tables.

Please help with the following points:

• When should we use standard, sorted, and hashed internal tables?
• What is the difference between READ TABLE, table expressions, and binary search from a performance perspective?
• How can we avoid SELECT statements inside loops?
• When should FOR ALL ENTRIES be used, and what checks are required before using it?
• How can joins, CDS views, and Open SQL reduce database calls?
• When is it better to use LOOP AT ... GROUP BY, REDUCE, FILTER, or FOR expressions?
• How can nested loops be replaced with efficient internal table processing?
• Which tools can be used to identify ABAP performance bottlenecks, such as SAT, ST05, SQL Monitor, and ATC?
• What are common ABAP performance mistakes that should be avoided in real projects?
• Can someone share a before-and-after ABAP code example for performance optimization?

A practical explanation with examples, performance comparison, and recommended coding standards would be very helpful.