I believe SoThink's code validates as strict XHTML. I was only suggesting if a site is going through a recode that alternate systems would be a good choice. As your menu system sounds like it would be quite large, and may grow in the future, then dhtml menus are definitely a good choice. I apologise if I gave the impression they aren't up to scratch, it's just that most sites I've seen implementing them actually use them for the eye candy rather than for functionality and actually clutter the overall design.
In your case, however, the choice is made for functionality
I'm still curious as to why moving file pointers would have any effect whatsoever on site speeds. If it is the case that moving a file from a subdomain to a main domain has a detrimental effect on speed then this might suggest that perhaps connections/limits are applied on a [sub]domain level as opposed to a per-account level.
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