I recently set up a VPS slice with 256MB to run a LAMP stack (Ubuntu 11.04, Apache2, Mysql, PHP5). So far I'm only running a simple Wordpress site on an IP-based virtual host I set up.

The performance is excellent, but I've noticed that if I send multiple HTTP requests from the same IP in a short time period, only partial pages are rendered. Then if I wait a bit and refresh the page, the entire page loads again. I noticed this behaviour when accessing the site from two browsers from my office desktop, but it also presents itself if I quickly navigate the site from a single browser (any browser).

I'm guessing this is an Apache phenomenon, as the pages are rendered correctly except under the conditions above, but perhaps I'm wrong here. Could it be my hosting company with some kind of DOS protection in place?

As a relative Linux/server noob, I'd really appreciate any insight into what settings in Apache could explain this behaviour, and how I might go about changing it.