ServerXMLHTTP request to same server

[Andrew Wilkes]

I have several ASP sites on a dedicated which send ServerXMLHTTP requests to a single ASP site (which I'll call "the target site") identified only by an IP address on a shared server . The setup works fine. Now I need to put all the sites on the same dedicated server. Microsoft advises against making ServerXMLHTTP requests to a site on the same server, however it suggests that if this must be done, then the target site must be in a different virtual directory and run in high isolation. I have created a domain for the target site and set all the domains (requesting and target) to have a dedicated IP pool. However, initial experience seems to suggest that there are problems with the performance of the 5 requesting sites; pages often load faster than before but the number of failed page loads has also increased. FTP connection also seems more unstable.
Unfortunately, I haven't been able to dedicate more than a few hours to testing performance: I would like to get advice or experiences on this, please.