Performance testing using Selenium and WebDriver is generally not advised. Not because it is incapable, but because it is not optimised for the job and you are unlikely to get good results. It may seem ideal to performance test in the context of the user but a suite of WebDriver tests are subjected to many points of external and internal fragility which are beyond your control; for example browser startup speed, speed of HTTP servers, response of third party servers that host JavaScript or CS...
