This paper presents results of the performance benchmarks of the Open Source hypervisor Xen. The study focuses on the network related performance as well as on the application related performance of multiple virtual machines that were running on the same Xen hypervisor. The comparison was carried out using a self-developed benchmark suite that consists of easily available Open Source tools. The goal is to measure the performance of the hypervisor in typical real-world application scenarios when used for "mass virtual hosting", such as hosting solutions of so called virtual private servers for small-to-medium sized businesses environments. The results of the benchmarks show, that the tested Xen setup offers good performance with respect to network traffic stress tests, but only 75% of the performance of the non-virtualized reference environment. This application performance score decreases as more virtual machines are running simultaneously.