To change the number of subrenderers while QuarkXPress Server is running as a service, open Regedit and modify the value located at:
HKEY_LOCAL_MACHINE >> SYSTEM >> CurrentControlSet >> Services >> QuarkXPress Server 7.2 >> Parameters
If you only have the two default Subrenderers that ship as a part of QPS, you will not be able to change the tasking for each Subrenderer. One Subrenderer will be assigned to WebHub requests, and one will be dedicated to handle Preview Generation requests. However, if you have purchased QuarkXPress Server separately with additional Subrenderers, then you can configure the number Subrenderers to handle specific rendering requests.
1. Changes to the Windows registry should be made only under the supervision of an IT expert.
2. Back up your Windows registry before making any changes to it.