Performance Issue with RTC

Hi There,
We deploy multiple instances of RTC on single machine, I really want to know whether such configuration is standard or supported one.
Multiple instances, multiple profile and multiple clients accessing it.
Environment:
IBM RTC 3.0
DB: MS SQL
OS: Windows 2008
Application: IBM Websphere
For one of the instance it takes time to load project dashboards, sometimes it is 2 Mins.
Do we have any performace patch we can apply for 3.0 series.
Let me know.
Thanks
One answer

do these all share a common Websphere? or separate instances?
we made a change this last weekend to a config parm in our shared Websphere that seems to have improved response time some for the RTC repository servers.
we saw a lot of errors in the websphere systemout.log file about VirtualHostContextRootMapper.
a WebGroup/Virtual Host to handle /ccm/rootservices has not been defined.
sam
we made a change this last weekend to a config parm in our shared Websphere that seems to have improved response time some for the RTC repository servers.
we saw a lot of errors in the websphere systemout.log file about VirtualHostContextRootMapper.
a WebGroup/Virtual Host to handle /ccm/rootservices has not been defined.
sam