Optimizing RPG programs

Just thought I would share this info, in case anyone is interested.

We have a batch program that Accounting runs several times at month end to
generate financial statements.  It is a Generalized Report Writer from JD
Edwards called "FASTR".  I won't bore you will too many details, but the bottom
line is that this puppy is a real resource hog.  So, we set out to find a way to
speed it up.

The RPG program was written several years ago and is still coded in OPM.  We ran
a sample job and checked the job statistics.
   CPU time consumed:  3684 seconds.

We recompiled the program using the *OPTIMIZE option and ran the report over.
   CPU time consumed: 3168 seconds.

Not a bad return (14% reduction) for very little work.  But we wanted more.  We
converted the source code to ILE and compiled it using the OPTIMIZE(*BASIC)
option.  Then, ran the report again.
   CPU time consumed:  2764 seconds.

One last test.  We recompiled the ILE program with the OPTIMIZE(*FULL) option,
and ran the report.
   CPU time consumed:  2350 seconds.

This gives us a 36% reduction in CPU time for this job, and we did not have to
write one line of code.

This particular program does a lot of heavy array manipulation, so I would not
attempt to generalize the results here and say that it applies to all RPG
programs.  However, if the shoe fits...........

Phil