JavaScript 1.8.5 (ECMAScript 5) adds some interesting methods that **prevent future modifications** of a passed object, with varying degrees of thoroughness:

 - [`Object.preventExtensions(obj)`][1]
 - [`Object.seal(obj)`][2] 
 - [`Object.freeze(obj)`][3] 

Presumably the main point of these is to catch mistakes: if you know that you don&#39;t want to modify an object after a certain point, you can lock it down so that an error will be thrown if you inadvertently try to modify it later. (Providing you&#39;ve done `&quot;use strict&quot;;` that is.)

**My question:** in modern JS engines such as V8, is there any performance benefit (eg, faster property look-ups, reduced memory footprint) in locking down objects using the above methods?

(See also [John Resig&#39;s nice explanation][4] – doesn&#39;t mention performance, though.)

  [1]: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/preventExtensions
  [2]: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/seal
  [3]: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/freeze
  [4]: http://ejohn.org/blog/ecmascript-5-objects-and-properties/

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Any performance benefit to "locking down" JavaScript objects?