Hello,
That is strange as printing plugin do not do any work in the background and it is not triggers by any events (nor front-end nor from the back-end).
I can assume that it would be possible if you would create tens of thousands barcode images and by some reason cache plugin would cache them all.
Could you disable our plugin, clear chache and monitor your website for a few days ? We need to be sure that cache problem was caused not by some other plugin.
In 2-3 days try to enable our plugin again and test it 24h more.
If you will reproduce this problem again then contact me here:
https://www.ukrsolution.com/ContactUs
then we will request from you more additional information to investigate this problem.