Any performance benefit to “locking down” JavaScript objects?

Question

JavaScript 1.8.5 (ECMAScript 5) adds some interesting methods that prevent future modifications of a passed object, with varying degrees of thoroughness:

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Answer 1

V8 has optimized Object.freeze as of Jun 20, 2013. And Object.seal and Object.preventExtensions as of Dec 10, 2014. See issue https://code.google.com/p/chromium/issues/detail?id=115960