Here is a helpful follow-up to the Twice as many fetch operations in Oracle 8i thread from a few days ago.

We experienced the same problem when we went to 8.1.5 from 7.3.3.4.

We use a lot of Pro*C code and modified $ORACLE_HOME/precomp/admin/pcscfg.cfg putting 2000 for the value of prefetch because we do a lot of array processing using 2000 records.

When we went to 8.1.7.1 this no longer worked and Oracle recommended setting the value for prefetch to 0 in the pcscfg.cfg file. This solved the issue for 8.1.7.1.