Whatever progress has been made, it still doesn't change the fact that Firefox has a much heavier and less agile codebase.
Either way, though, competition is a good thing and can only benefit the consumer.
I wasn't aware that the fastness and lightness could be better than ever compared with one thing, and not when compared with another.
It's got better lightfastness! So, the Mozilla browser will degrade less over time in direct sunlight!