Is there a way to force caching of index.php?

Hi,
I have problems with the main page (index.php) of my site. It loads only after 3-4 seconds of waiting.

I use WP SuperCache. The problem is, the content is refreshed very often, so many of the visitors don’t get the cached version, and they have to wait for these 3-4 seconds before anything shows up.

Is there a way, is there a plugin, by means of which I could force the index to not be refreshed for, say, 10 minutes?

Really, really hope you could help me. Thanks in advance!