Safari keeps downloading data when Gmail is open If I have a visible tab (non occluded window) open on Gmail, my Safari (8.0 running on Yosemite) keeps downloading data at a rate of 1 MB/s. The same does not happen with Chrome.

I'd like to understand what this is for, and if possible, make it stop.

Some info:


logs don't show anything suspicious. 
caches are ok
network panel of web inspector shows no activity
lsof output: https://gist.github.com/Agos/78fa61943af31d634a99
Disabling Chat in Gmail looks like it sovled the issue for me.