Ctrl + shift + R would solve your second problem at all times.

And I don't think your first point is quantified correctly and I am sure there is no data to back it up. But I understand the appeal of trying to quantify your personal experience.

I can back up their first point a tiny bit with regards to canvas. The primary product of our company is heavily canvas-based so I’ve always noticed that canvas on Firefox on macs is slower than on Chrome but it used to be in the 2-3x range and nowadays is more in the 1.5x range. They’ve made great improvements and I’ve never noted anything close to 5-10x slowdowns.

On Windows Firefox and Chrome canvas has performed equally well at least for the past ten years. Got no data for linux tho.

Yup, or open dev tools and enable "disable cache". This applies only while dev tools is open