I used to wonder why my ThinkPad sometimes ran for 12 hours and sometimes 5. Turns out that Google Docs has an animated cursor that doesn't just blink, it fades in and out using javascript. Animation cost several W on average. UX guys love animations because I dunno they are just psychos.
My office decided to move from Jabber (Pidgin / Adium) to Slack. Much of the office upgraded computers. Whether Jabber is negligible, Slack used más two to three Gb RAM. It’s simply the most inefficient software I have to Tun continuously on that PC
Their priority was probably shipping a cross-platform app as quickly as possible and gaining adoption. My hunch is they will eventually make native apps for Windows and Mac and drop Linux support.
It's less of a joke and probably just a statement.
Seriously: even something as small as someone adding an animated emoji makes slack eat CPU :-/