Let me guess... they haven't packed the database since the original developer left the company?
Zope scales quite well, in my experience... I'd wager whatever problem you're having is probably some easily-fixed configuration or maintenance issue. It may be too late to argue that point, but I think you'd find a lot more help being offered if the client were interested in fixing the problem instead of blaming the software. Not your fault, probably...
This application provides the option to pack the database and I have packed it myself too. But it is, still, too slow. Earlier programmer, who originally accepted this project to port this app to php/mysql, did extract data form zodb and has already written the same application in php. Speed and performance of the php-mysql is much much better. I am not blaming zope as I don't know much about it. But as I had to add more options to this application, I have to extract that data again. Earlier programmer, somehow extracted the data for himself only to write application in php. He did'nt write any script for client to export that data themself. But I need to provide client this option of exporting because they are using the system at this time. --Sukhwinder Singh