[Plugin: WP Super Cache] Force the plugin to always serve a cached file

Hello,

I have the following issue with WP Super Cache plugin.

When Visitor 1 load the page: “test” a cached version is correctly generated and it is sent to the browser. This takes around 9 seconds due to a know issue in WP. Please see: http://wordpress.org/support/topic/345125?replies=3
When visitor 1 reload the page “test” the cached version is sent to the browser. This takes around nothing.

So here everything is working fine, but:

When visitor 2 load the same page “test” a new cached version is generated and this takes again around 9 seconds.

Following this behavior the plugin is helping the load time only when a visitor is reloading the same page.

How I can force the plugin to always send the cached version generated the first time with visitor 1?

Log:

Setup:
WP 2.9
WP Super Cache Version 0.9.8
ON WP Cache and Super Cache enabled (Tried also with the HALF setting)
ON Cache rebuild (Tried also with off, nothing changed)

I have a Mod Missing: mod_expires (I can’t install it right now) but as far as I know it shouldn’t be a part of the problem I’m experiencing.

Thanks!