Wildly inconsistent performance

We have a package that does a series of lookups, and returns a single result.

I have a script that makes 10 calls to the package with different input. I use timex to time the 10 calls. Sometimes, they return in less than 2 seconds (total time for 10 calls). Other times, it takes over a minute for the exact same test data. It tends to have two speeds (slow and fast), and it gets stuck in one speed or the other for extended periods. For example, it will take 2 seconds for each of 20 runs, then 1 minute for each of the next 30 runs, then back to 2 seconds.

I've run bstat/estat, and nothing looks amiss .... 99% hit ratios, no latch contention, no RBS contention, no waits, no nothing. The database is fairly low activity (typically 20-50 connections), and I don't see a pattern of something else running at the time of the slowdown.

I've also monitored it a little at the OS level (not my specialty), and don't see any disk, memory or swap issues either.

I'm running the tests directly from the server, so network/connection issues are eliminated.

Any other ideas ??

Database : 8.1.6.3.0
OS : Solaris 5.8
Veritas Cluster Manager 1.3 Received on Tue Nov 27 2001 - 13:04:41 CST