Performance deteriorates on a dynamic db

Hi, Oracle Experts,

We have an Oracle 7.3 on NT 4.0. There is one schema we use a few stored procs to insert, update, and then delete a lot of data all the time
(10,000 to 40,000 rows on half dozen tables). It seems Oracle gets slower and slower each we do another batch of insert. Truncate and delete all the tables manually did not help. Drop the schema did not help.
Uninstall and reinstall the Oracle server would regain the better performance but it would then deteriorate over the same operation.

Does Oracle have problem with a dynamic database? Do I need to recompile all the store procs ? Thanks in advance for the help.

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Phil Tsao
philt_at_technologist.com