Hi, I am running several dnn sites that make heavy use of the xml module. And have been having serious speed issues. We tried increasing memory on the server (up to 3Gig) and suddenly everything fell apart, like the server is completely locked up. Dropped back to 1G and things sort of work again but are painfully slow.

I have one server (MS 2003) with IIS 6.0 and .NET 2.0.
have several sites runnning on this on one IP number, using host headers to connect the domain names to the proper dnn sites.
3 DNN installs: one older one with DNN 4.5.5 serves 4 sites, minor xml use.
2 DNN 4.9.2 sites each with very heavy xml module use: up to 4 xml modules on a page, almost all content delivered in xml files (most saved as static files on the server to save the fetch time from the xml source server).
www.wycliffe.net
www.thewordislife.net

this KB article from MS seems to speak to this issue:
Contention, poor performance, and deadlocks when you make Web service requests from ASP.NET applications
http://support.microsoft.com/kb/821268

what do you think? Should I be tweaking the threads settings in my .net setup? sure sounds like it to me.
does each IIS site get its own threads or are all sharing the same .net pool?