I actually don't know how much of an effect cache should have on performance, but the article mentioned the "disable cache" not working as having a negative effect for him, so I assume it was because he thought it made things slower for him.

Your second point is a good one. I didn't know!

I'm not sure what you mean by your last point. Include two browsers? Do you mean that I mentioned Canary? I didn't consider that specific to my point. Yes, I know FF has dev versions as well.