Let’s assume you have written some code, it’s working, it computes the results you need, but it is really slow. If you don’t want to get slowed down in your work, you have no other choice than improving the code’s performance. But how to start? The best approach is to find out where to start optimizing.
It is not always obvious which part of the code makes it so slow, or which of multiple alternatives is fastest. There is the risk to spending a lot of time optimizing the wrong part of the code. Fortunately, there are ways to systematically test how long a computation takes. An easy way is the function
system.time. Just wrap your code into this function, and you will (in addition to the actual results of that code) get the time your code took to run.
But that’s not the only route—read on to learn about other techniques as well and see them in action.