Yes ... your site is a dog ...

Unfortunately, I see nothing about your site to account for this issue ...

Other than being on an overloaded server with your hosting company, I really don't see why it is this slow ...

What version Zen Cart is this?

Can you look in the Admin ... Tools ... Server Info ...

Does it tell you the Server Up Time?

Was it just recently rebooted as in a current date and time?

It was horribly slow a couple minutes ago and now is moving ...