Are frozen Objects faster ?

Andrea Giammarchi andrea.giammarchi at
Thu Feb 14 12:36:27 PST 2013

the `delete` changes the shape of the object, right? so I
think is more a problem of devs using objects as trash bin but this is the
opposite scenario of a frozen object.

I understand ES5 descriptors are an overhead during an object lifecycle but
I think a mechanism to make frozen object that fast would be a win while we
wait for better options on statically defined types.

"Binary Arrays" are indeed frozen objects, at least in Firefox, and ultra
Object.isFrozen(new Float32Array()) // true in Firefox

Since these are ultra fast in Chrome too but not frozen, I believe there is
already a way to speed up typed stuff (didn't check how it's done though)
so I wonder how come Object.freeze() is not taking similar approach
"typizing" behind the scene the object improving all static properties
getters (probably dropping those getters where possible unless defined as

Will this cost more than now at freeze() time? I understand this might be
undesired but think about libraries or modules that do not want to be
extended, would like to be as fast as possible, and are loaded once and
never again.

Thanks for all thoughts and info already provided, also agreed on some
I usually do that on jsPerf 'cause I don't know how to reach those bigger,
widely tested, one.

Any hint here appreciated.

On Thu, Feb 14, 2013 at 12:24 PM, Andreas Rossberg <rossberg at>wrote:

> On 14 February 2013 21:12, Kevin Gadd <kevin.gadd at> wrote:
> > I'm pleased to report that Object.freeze does not seem to cause an
> > enormous performance hit in v8 anymore. Hooray! Unfortunately, the
> > call to Object.freeze itself shows up as a bottleneck in V8 profiles,
> > and the 'freeze enabled' version is slower in both versions (though at
> > least only slightly slower).
> Thanks for doing the benchmark, very interesting!
> That freeze bottleneck will hopefully vanish in the foreseeable future.
> /Andreas
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