Deprecated - Performance and scalability

I have installed 4.6 on a hosted web server. The cache has been enabled. Why the logo of the site keep reloading if you use the back and forward on the broswer? Both IE and Firefox. http://geti.unitedframes.com/

The 403 error page, could not been displaied. It said a 500 internal error. Check my site. http://geti.unitedframes.com/kkk

We are running a Drupal 4.6.3 site on two (!) modern dual-Xeon front end servers (Apache 2.x and 2 GB RAM) and one modern dual-Xeon database server (MySQL 4.x and 4 GB of RAM).

Running one Drupal community on two front end servers is probably quite unusual. We are using a hardware load balancer that sends every second user to one server and every second to the other. Both servers have access to the same Drupal- and user files trough a shared disk array that both servers have mounted. This solution works flawlessly and makes Drupal truly scalable. At least as far as the front-end is concerned. So far so good.

The database server with its dual-Xeon and 4 GB of RAM should be able to handle anything we throw at it, but this is not the case. When we reach about 50 authenticated users or 25 page impressions per minute, the server locks up with slow queries that takes hundreds of seconds to complete. This despite the processing power and the fact that the server is able to keep the entire database in RAM. We are expecting more from this hardware.

The community has something like 40.000 nodes and 60.000 comments.