At the moment, two tools are living together to test and generate performance reports.
The first one is MS-Perfs which allows to compare QGIS Server with other map servers (like GeoServer or MapServer). Reports are generated weekly and available here.
The second one is Graffiti, allowing to generate a performance report between several versions of QGIS Server and/or specific project options (parallel rendering effect, trust option, and so on). Reports are also generated daily and available in. Note that QGIS-Server-PerfSuite project is the deployment infrastructure to run Graffiti in continuous integration.