Loading indicator using a lot of CPU

[tosh]

I recognized my Macbook getting a bit hot and looked into the activity monitor:

When I switched to Atom to see what's going on I found that it was still showing a loading indicator from a form that I evaluated previously. As soon as I made the loading indicator go away (copying, deleting and pasting the surrounding text) the CPU usage dropped back down.

Semi-unrelated: It seems like sometimes the loading indicator is sticky, I usually just delete the surrounding text and paste it back into the document to go away but I didn't notice this time so It kept animating for a few minutes until I noticed the laptop heating up.

How to replicate

add the following to your file and then evaluate the form

(Thread/sleep 1000)