It's not worth it to them precisely because the vast majority of web traffic is served over HTTPS. You can bet they would these days if most traffic was HTTP
I wonder if you could roll your own VPN tunnel that directly connects to your home internet IP and passes custom encrypted payload that your IT department cannot decode. Would they just drop the connection if they can't inspect what your are sending?
My CPU was at 27% (i3-4130) and 27 watts power use vs. 11w at idle. Added uBlock filter: github.com##div.signup-stars and CPU was back to 1%. Background stars animation is the culprit.