I highly advise you compress the folder, 7-zip is a good pick if you don't mind getting a new tool, otherwise just right click and do the low quality send to compressed (zip) folder built into windows. Highly played world files are fairly big and it has 2 copies of that.

another reason to use 7z is you can use the command line version that comes with it to do a batch file backup in your task scheduler. Really easy daily (or hourly, whatever) backup when playing, but if not playing anymore, no point.