It appears that for the phones that attempt to use AGPS to get a fix take longer to get a fix than the phones that do not use AGPS. As the OP posted, disabling AGPS in the registry seemed to help.
I found a great link which helped me with the Lag on my Touch Pro and also gave me more sats to lock onto. Hopefully the information could help you too.
I found this page about a week ago and it seems to work better than everything else I have tried.
http://blog.mohdimran.com/htc-touch-...blem-tweaking/