Actually, I believe there has been quite a lot of performance enhancement done in the late 5.x and 6.x versions.  

I am sure there is some tweaking that could occur for caching that would help your page load times.  Sometimes shared hosting throttles one resource or another and so its hard to state across the board which configuration would be best for everyone, there are some variables.

The login time you are experiencing is particularly interesting, there is no reason for this to be so slow.  Login actually performs a "postback" as part of its function, could you try some other functions which involve a postback (like settings updates or file uploads) and see if they have similar response time?  Does a second login (different ID) after the first happen more quickly?

I know that there will be lots of suggestions for you, with a little more information folks can help you diagnose.

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Scott Willhite, Co-Founder DNN

OK, it's starting to get late here in the UK, so just had time for testing the logins on both installs.

First login as Host took about two minutes and navigating around was slow.

Logged out, logged in as Admin, which happened pretty quickly, as was general page navigation and access to Admin modules.

Logged out, logged in again as Host, again pretty quick as was navigating etc. How weird is that?

I will continue testing tomorrow, time for dinner and down time now!