We’re are also not talking about a few megabytes here and there, but we are talking about gigabytes! The folks at ArsTechnica have managed to reproduce the problem themselves and in their findings, they found out that the app was writing as much as 5-10GB of data per hour, which means that within a few hours one could easily consume as much as 50GB just by streaming songs.
Thankfully Spotify has since managed to jump on this problem and have released an update. If you were to update to version 1.0.42 of the desktop app on Windows and Mac, it should stop the problem. Apart from it being a waste of space, it also reduces the lifespan of hard drives simply because every hard drive has a finite number of data it can write before it “breaks down”.
If you haven’t downloaded the update already, then perhaps you should. You’ll be able to check which version of Spotify you’re running and pull the update manually by going to Preferences and selecting “About Spotify”.