Hi Daniela,
Actually I am using the JMeter Load testing plugin to Moodle report.
You can download it here:
http://www.open.ac.uk/blogs/XHProf/?page_id=64
I am using Moodle 2.3, so I am not sure if it will works on your Moodle version. This tool is very easy to use. You just need to go to your Report, then select the JMeter loadtesting from the report list then select what do you want to test, then it will generate the script for you. You can open the script with your JMeter, then you can modified the script base on your requirement.
Regards,
Yulstar