First time loading was slow, really slow. Second pc, it loaded instantly (this is after the first one loaded it really slow).
I get the same thing too, and when I open a different browser it still loads quickly. I also tried it on a separate test line we have here on a totally separate computer using the Google DNS servers, and it pulled up quickly too.
I think the reason is on the server. I think the PHP cache is expiring on the server, so whenever you go there the http server has to compile the PHP before it can server the webpage. Every request after that will used the compiled versions that are stored in the server cached.
The speed of the compilation is directly affected by the method used for compilation. mod_php is the fastest method for serving PHP, but it's also kind of insecure since it runs as the webserver user. Fast CGI is slower, but it is more secure since it runs as the owner of the files. Since this is a shared webhost, the webserver might be setup to use Fast CGI for security purposes.
These are just guesses, and you'll have to see how the server is setup.