Despite protestations to the existence of a ZCatalog caching tool I've finally released it to http://pypi.python.org/pypi/collective.catalogcache :) A disclaimer is on order here: I agree that there are many other places where performance needs to be addressed and that catalogcache masks those areas; however, it works well and should solve performance problems on sites with expensive queries. Andreas Jung, Christian Theune and Roche Compaan gave me a few great tips - thanks for that. Roche has also done benchmarking with it. Andreas asked about the hit rate earlier. Memcached itself operates at a 96% overall hit rate. Individual Plone catalogs (portal_catalog etc) vary, but they usually run at above 90% hit rate with portal_catalog dropping to 80% in cases. This is of course dependent on the usage pattern of the site. So give it a go, or shout at me and tell me that it is a bad idea :) Hedley