Reading the paper in that link I gave is a good start to understanding how the SQL optimiser works. I hate to say this but there are no magic bullets when it comes to performance tuning, and especially so with SQL. One thing to look for when using _METHOD is to see if SAS is doing table scans on joins instead of indexed joins. Table scans are way slower. It could be you are missing an index, resulting in a slow join. Only careful checking will uncover the true reasons. ... View more