The HTML version of Gmail is also very dense, maybe even the densest of all Gmail versions.

I only use html gmail. Not because the default GUI is bad, but because its too heavy. Look at these numbers. I just opened here, clicked nothing:

"393 request, 5.7 MB transferred, 34.3MB resources"

It's crazy.

It's an SPA, so it's more like `apt install` than a normal page load. Much of it sits in cache afterwards, and the traffic is reasonable.

What I do dislike about Gmail is its propensity to consume CPU sometimes, but it's not the worst offender.