Any rewrite or big change is a gamble. By setting this metric they avoid performance degradation. I'm admitting that I'm just assuming this, but the changes are

Any rewrite or big change is a gamble. By setting this metric they avoid performance degradation. I'm admitting that I'm just assuming this, but the changes are probably a start for easier future optimization. Setting two big targets: make it a lot faster and make it a lot better, seems to me like a mistake.