closed → reopened
You could work around that by first trying to use the native JSON on the raw string, and only in the case of failure perform the sanitizing. Then Chrome users could still benefit from the low overhead as long as the JSON is not problematic (which should be most of the time).
Duplicating the browser work by default still seems strange to me, though I don't know how large the performance impact is in the average case (in my case it was fatal).
Taking the argument to the extreme would imply that jQuery should implement its own HTML rendering engine just to guarantee "consistent" rendering across all browsers.
Please reclose it if you still disagree, I won't open it again, sorry for the trouble.