I have been given the task of optimizing the performance of a block of code (too large to be copied here). Currently, the code contains a mix of SCAN..ENDSCAN loops and DO WHILE..ENDDO loops. Some of the WHILE clauses are not Rushmore-optimized, so normally my first step would be to replace these with optimized statements. In some cases, however, this may not be possible.

While I'm at it, I was going to replace the DO WHILE..ENDDO loops with SCAN..ENDSCAN. However, someone mentioned to me that when using non-optimized statements, a DO WHILE..ENDDO can actually give better performance than a SCAN..ENDSCAN. Is this true? I've always used SCAN..ENDSCAN, but some of the legacy code I'm looking at uses DO WHILE..ENDDO.

Bill