All true, but the file system should not play a big role in my tests. (For the first test, the row should be in DB2's cache; for the second test, I have clustered the table on the key I have searched for, such that all 100,000 rows are on the same location on the disk.)

Also note that the speep-up I have observed when upgrading from the Fedora to the SUSE perl packages (all on the Fedora system), was a factor of 10, even if I made no other changes.

So I guess this is not a problem with DB2, but rather with perl accessing it.