Why is your code slow?

Reading and writing data to the hard drive takes much longer than reading and writing to RAM. This means if you need to retrieve data from the hard drive it takes much longer to move it to the CPU - where it can be processed - compared to moving data from RAM to the CPU. A program's use of resources, like RAM, processors, and hard drive dictate how quickly your R code runs. You can't change these resources without physically swapping them out for other hardware. However, you can often use the resources you have more efficiently. In particular, if you have a data set that is about the size of RAM, you might be better off saving most of the data set on the disk. By loading only the parts of a data set you need, you free up resources so that each part can be processed more quickly.

Which one of the following does not contribute to processing time?