I recently learned about a Chrome Extension that CodePen peeps might get some good use out of. It's called The Great Suspender. The idea:

Automatically suspends unused tabs to free up system resources.

After a tab goes unused for a while, it gets replaced with this:

Which you click to go back to what that tab was showing. The reason I mention this extension here is that, if you're like me, I have a bunch of tabs open all the time, sometimes to the detriment of my computer's memory and CPU. That problem is a liiittle bit exaggerated since a lot of those tabs are Pens, which can sometimes be, shall we say, computationally intense.

I've been using it about a week on CodePen and it seems pretty safe. Meaning, it won't suspend tabs with unsaved work.

It also has a nice set of settings to customize things to your liking:

Enjoy!