If the database is a very active one, then what happens was that the one DBWR process that has to do the work of reading and writing. If your reports are going to put in some load the DBWR would be a slowdown point. This would be the general notion. Now further, as I said above, I strongly would suggest that you run the statspack during the regular time and one when running the report. then do an analysis and see where exactly the cholk point comes from.

Hope this would explain.

Sam