GlobalEye is an aircraft by Saab that provides surveillance of air, sea, and land. In order to train on the system present in this aircraft a Mission Training System, MTS, is used. The MTS consists of the Command and Control, C2, system that is present in the aircraft as well as a scenario simulator. This master thesis is focused on evaluating the performance of the distributed real-time system that is the MTS in terms CPU and memory usage of its Java processes. These Java processes are divided across four servers and two types of workstations.  Two sorts of tests were conducted; workload model testing and user scenario testing. Both tests were conducted multiple times with different amount of workload. The workload was defined as a number of air and sea targets added to the scenario simulator. The data was collected by running bash scripts on each machine that saved the CPU and memory output from the Linux top command. Java VisualVM was used to examine a selection of processes further. In Java VisualVM the heap size, garbage collector pauses, and CPU time of the methods were the main focus of interest. The result from the workload model testing showed that a large majority of the processes handled an increased workload in terms of memory usage well. When it comes to the CPU usage four processes with significantly increasing CPU values were examined further in Java VisualVM. These processes were MMI processes and processes involved in data transfer. No problems were noted regarding the garbage collection and heap sizes. The longest pause, across all processes, caused by garbage collection was 29.7ms. The methods with highest amount of CPU self time were also identified for the processes. One observation was that a method related to map rendering, for the MMI processes, showed decreases in CPU time as the workload increased. The result from the user scenario testing showed that the MMI of the scenario simulator suffers delays dependant on the number of targets present in the scenario. The Java process of the MMI did increase its CPU usage significantly as the targets increased. In Java VisualVM it was observed that the garbage collector for the scenario simulator MMI process was more extensive during these tests, with the longest pause being 104ms. Lastly when it comes to the CPU self time of the methods within the MMI process, one error related method was identified.