When making changes to a site or server that may affect performance, it is good practice to run a benchmark before and after the change. This will help to quantify the effects of the change. This article covers using Apache's ab program, which is documented further below.
To perform a benchmark, run the following command as root on the server. The n value represents the total requests to make. The c value represents the number of requests to have active at a time. http://domain.tld/ represents the URL to request. In cases of testing general server performance, you will want to test a few URLs that are representative of your server.
ab -n 100 -c 10 http://domain.tld/