You could do this with a "splash" page, but it's likely not going to display that page until the site is loaded.

You should work on issues related to loading. It this is the initial load that you are describing, then you want to add a "keep-alive" service to keep your site loaded. That's the easiest way to improve loading time.

Next, Google "DotNetNuke performance" and review the first 5 or so pages. Mitchel Sellers tips work. Pageblaster helps get the last ounce of performance out of DotNetNuke sites.

have a read of this forum post:
Performance Tips - Fast Site - Keep Alive Tools - Hosting

from the site I viewed, initial load time of the website was slow, so I really recommend you use a ping service as mentioned in that forum post.

After that yes, your pages are loading slower than a DotNetNuke website should, if that is still the case after implementing page blaster, it could be worth having a look at a different hosting provider.