Performance problems with large SELECTS in 7.3x ?

Hi, I tried to select some pages of a table that was a bit larger than my buffer pool. I estimated that my statement will take about 5 seconds but it took 12 seconds. I found out, that the server spent approx. 7 seconds for "buffer waits". Now I added a few buffers to the buffer pool so that the buffer pool was a bit larger than my table and started the Select twice. The 2nd Select took less than 1 second. So I'm sure it's not the regular buffer access where I lost my 7 seconds. I know that starting with version 7.3x Informix is using 4 priority levels in the LRU-queues and in my opinion this new feature costs a lot of time, because I always spent the additional 7 seconds when the pages had to be loaded into the buffer pool. Any comments ? I ran the test on a HP-UX 10.20 / IDS 7.30UC2. Is there anybody who has made similiar experiences ? ( When I set LIGHT_SCANS=FORCE, the Select statement took really 5 seconds. So I think my estimated duration time was correct ). Bye Stefan Weideneder