Ok, I can understand how different installations could affect the performance of the theme.
Here is the URL for the site: http://brynsconsulting.com/tiki-index.php
As I said, i am experimenting. I want to get this theme working before doing any more to the site.
I haven't changed the css. I've only messed around with the various "look and feel" options, so far.
Re-edit: I noticed a 1 pixel break between the header and body - only when logged in. I thought it was just a glitch in the png/jpg but when looking the site over in IE, I noticed that the header/body match is smooth. I wonder if this is an indication of the "invisible intrusions" you mentioned.