Why should the user need to do that? The browser should automatically configure itself for optimal performance on any reasonable hardware.

Because none of what they talk about is a problem. So the problem may lay on their side. Or they roll on a half-a-decade-old sentiment.

Firefox does, though. There really aren't these wild and crazy speed issues with it at all, even with fresh out of the box defaults.

The only time I've had to touch about:config in the last several years was due to some smartcard related bug caused by an external library, that forced me to tweak firefox's behaviour. Once that bug was resolved, I switched it back.

Firefox being slow is well into the self-perpetuating FUD territory.