How to speed up R code in RStudio

I just found out by trial and error that the suppressing of print statements in RStudio greatly speeds up the R code.

In my case, code that was originally estimated to take around 40 hours to run,  just ran in under an hour after I suppressed all the print statements in the for loops.

This is supported by evidence in other forums, for example in StackOverflow: R: Does the use of the print function inside a for loop slow down R?

Basically, if your code prints too much output to the console, it will slow down RStudio and your R code as well. It may be due to all the output clogging up the memory in RStudio. R is known to be “single thread” so it can only use 1 CPU at a time, even if your computer has multiple cores.

Hence, the tips are to:

  • Reduce the number of print statements in the code manually.
  • Set quiet=TRUE in all scan statements. Basically, the default behavior is that scan() will print a line, saying how many items have been read.

This is especially true with for loops, since the amount of printed output can easily number to the millions, and overwhelm RStudio.