Performance improvements have diminishing returns though, and for a consumer product like Firefox, a large number of users will be on older hardware. Ceteris pa

Performance improvements have diminishing returns though, and for a consumer product like Firefox, a large number of users will be on older hardware. Ceteris paribus, it would be much better to get say a 10% improvement for the users on below-median hardware than for the users on above-median hardware since it will matter a good deal more for the former group.