Dear all, I'm running a large Zope application on a 1x1GHz CPU 1GB mem Window XP Prof machine using Zope 2.7.3 and Py 2.3.4 The application typically builds large lists by appending and extending them. We regularly observed that using a given functionality a second time using the same process was much slower (50%) than when it ran the first time after startup. This behavior greatly improved with Python 2.3 (thanks to the improved Python object allocator, I presume). Nevertheless, I tried to convert the heap used by Python to a Windows Low Fragmentation Heap (available on XP and 2003 Server). This improved the overall run time of a typical CPU-intensive report by about 15% (overall run time is in the 5 minutes range), with the same memory consumption. I consider 15% significant enough to let you know about it. For information about the Low Fragmentation Heap, see http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base... Best regards, Martin PS: Since I don't speak C, I used ctypes to convert all heaps in the process to LFH (I don't know how to determine which one is the C heap). ________________________ COMIT AG Risk Management Systems Pflanzschulstrasse 7 CH-8004 Zürich Telefon +41 (44) 1 298 92 84 http://www.comit.ch http://www.quantax.com - Quantax Trading and Risk System