Performance degrades as time goes by
Hi
We see performance on our 9i db degrade as the day progresses. When db first starts, our test queries run in seconds. As day proceeds, performance gets worse. Even row counts slow down considerably. The only thing I see is a buffer cache hit ratio in the 93% range and I see our buffer cache has all blocks used by 10 am. 90% of blocks are usable, but have been used by that time. I'm suspecting high churn on the buffer cache.
Any thoughts or assistance would be appreciated.
Our buffer cache is currently at 1G.
all os perf counters are fine, cpu sleeping, no paging, no high disk queue, etc.