Hi,
I would be very interested to see how your problem works out, and any possible solutions. I had a DNN site hosted there for about a year, but also had performance issues. I was getting RSS feed errors timing out all the time and about a dozen errors everyday from host tracker ping service not being able to reach my website.
I was disabling schedule items, disabling rss, ran under an isolated app pool, deleting uneccessary modules, and was still lacking in acceptable performance. My site is a tiny website and hardly busy, and WSS was always pointing the finger at my DNN install when i voiced concern about declining performance.
In the end, i moved to a virtual dedicated server running 512mb. On the server, i have plesk installed with all the included services, ms sql express, my DNN website, and a friends php based site. My site is now MUCH faster, never times out, and i am back to running DNN with all the bells and whistles. I have only been on this account for 2 months, but love it so much, i am looking to go to a full dedicated server, and hopefully share it with a few friends. 512mb is tight, but i am getting by just fine, at least for now.