We are running a forum software (Woltlab Burning Board) on our server and found out that if at least two users keep reloading the website very quick (keeping F5 button pressed), the server load goes up to > 15, leading to really slow server responses.
We also tried it with a fresh forum install without any plugins with the same results. The load seems to come from apache and not from the database (MySQL) or anything else.
The server has the following hardware which should be more than enough: Intel Xenon 4x3,3GHz 16GB RAM
Screenshot of the apache load while F5 pressed: http://imgur.com/hc3RpbF
How could we prevent such a high server load? Thanks in advance