Hi Lennart My problem is (still) the threading of Solaris (see thread on performance and threading or the Threading Report http://www.zope.org/Members/glpb/solaris). Usually I just have two Solaris machines to play with and now I had two Linux PC's aswell. One was on RedHat 7.2 with Py 2.1.2 and Zope 2.4.4 from source and the other was Py 2.1.? and Zope 2.4.1 precompiled. The problem I had with Solaris is that it seemed to be singlethreaded! You run a big "job" on Zope and try to do something with the management interface (or anything else on the site) and it won't work in parallel. I used to think that it is a Solaris problem. But the Linux RedHat machine has the same problem. Now I noticed that the problem does not surface when I use precompiled stuff (Suse Linux machine - or WinNT I tried earlier). Therefore it MUST be my build of Python!! Now the thing is, where did I go wrong?! As I understand it it must be as simple as you said but since I had the same problems with 3 machines of totally different types and *NIXes my error must be quite obvious.... Was that detailed enough for you to give ma a hint? Thanx for the help Oliver Erlewein