If they are running slow the first time they are run them then that is likely that some of the tables (or columns used) have been offloaded from memory previously, and need to be reloaded on the first run.
http://scn.sap.com/thread/3518051
If they are running slow the first time they are run them then that is likely that some of the tables (or columns used) have been offloaded from memory previously, and need to be reloaded on the first run.