increasing effeciency of programs thru optimized coding
eg : select ... table itab...
    instead of 
     loop at itab 

        select ,...into itab..
      endloop

Performance tuning means analyising the performance of the 
program.

Performance of the program depends on the data transfer.

By reducing the amount of data to be transfered, we can 
improve the performance of the program.

Performance tunning.

There are various steps to increase the performance of ABAP 
report.

* should not use * in the select query ,instead use the 
appropriate field names.
* In the occurs clause avoid using 0 instead use the number.
* try to use move-corresponding .
* use the aggregate statement.