[Zope-dev] Site error

Hi, I have three web sites hosted in the same server with 4GB RAM and enough storage. The third web-site hosted recently requires high processing and heavy scripts are running. Basically one of the script communicates with 2 databases and fetches the results. The heavy script runs for 3 minutes. the CPU occupies 183% or more for that script. Until it complete the script the web-site goes down with proxy error, where httpd is running and zope is also running. Only after restarting either zope or httpd, all the three sites are accessible. Could you please suggest me solutions to optimize the sites? Any pointers in this regard is highly appreciated. Thanks and Regards, Babylakshmi