Caching at the HTTP level is much more efficient. If you publish your data as static files, you allow the web server to work in the most efficient way possible. You can also use a caching proxy like apache's mod_proxy module.

Caching in the application gives you more control, and allows you to cache just a part of a page instead of the entire thing. I would recommend you look at Cache::FastMmap instead of Cache::Cache, because it's much faster.