[Zope] Problem of performance

Hi, It's strange, I thought I was rid of it, but it seems to pop-up now and then. I'm talking of a slow performance of Zope2.2.x Here is the problem: When I'm working in Zope, the following happens sometimes : eg. I copy an object and then try to paste it. The pasting can take minutes, or the interface just keeps trying to load the page. Now, when I stop the loading of the page (when it seems to be hanging) and reload the page, I see the copied object. So, it looks like Zope has problems to display the page. I've Zope installed on Mandrake and the problem occures on Netscape (Linux) as IE5.0 windows. Somebody an idea what may be the cause of this? Did something changed in the code related to this? Thanks in advance, Tom.