Yes, thinking about performance, linking external modules for simple task may not be a good practice.

no libraries exist for a specific purpose they are tools that are ment to be used in many cases they are there to speed up code that you yourself may or not be able to tweak on your own, also they keep repetitve coding down by haveing chunks of code callable so they dont have to be written over and over. numpy, pandas, and sipy are awesome libriaries, I have used numpy on this site I dont think it links to psycho which is ment to be a psychological library , I tried to use it once and it showed the no psycho error on both 2 and 3