I upgraded from mysql-3.23.56-1.9 to mysql--4.0.20-0 using the mysql.org RPMS, from Zope 2.6.2b3 (Python 2.1.3) to Zope 2.6.4 (Python 2.3.4) under Linux RH7.3 with kernel 2.4.20-28.7. Host is a dual Athalon processor with 4GB of memory, 3ware RAID (configured as RAID 10) and not much else. Performance is way down from the earlier configuration with "bursty" slowdowns. There is some evidence that it is somehow related to redirection in the Zope application, but we have not been able to locate the problem. Has anyone else experienced this sort of problem? Pointers and suggestions would be appreciated. It is possible that the behavior could arise from a different kernel (and different scheduler) and the GIL (Global Interpreter Lock). We have several years experience running Zope on a dual processor machine on RH7.3 without observable GIL problems, but it is a possible source of the problem. Does anyone have a suggestion as to how to determine if that is the case?