Maximum PC posts a thorough guide on properly benchmarking your PC.
For those not in the know, benchmarking is the process of "running a computer program, a set of programs, or other operations, in order to assess the relative performance of an object, normally by running a number of standard tests and trials against it." (Wikipedia)
As Maximum PC says, "To care about benchmark is to care about performance. And to care about performance is to care about having more free time on your hands."
So if you're looking to maximize your PC's performance and save some time in the long run, click through to read.