# Speed difference when storing annonymous function in variable vs. function

**URL:** <https://discourse.julialang.org/t/speed-difference-when-storing-annonymous-function-in-variable-vs-function/36350>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [March 22, 2020, 4:25pm UTC](https://discourse.julialang.org/t/speed-difference-when-storing-annonymous-function-in-variable-vs-function/36350 "2020-03-22T16:25:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![anon32405968](https://avatars.discourse-cdn.com/v4/letter/a/57b2e6/32.png) [@anon32405968](https://discourse.julialang.org/u/anon32405968)\
**Post date:** [March 22, 2020, 4:25pm UTC](https://discourse.julialang.org/t/speed-difference-when-storing-annonymous-function-in-variable-vs-function/36350/1 "2020-03-22T16:25:58Z")

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Apologies if I am making a mistake with my benchmarking here, but I am wondering why there is such a significant speed difference between using an annonymous function stored in a variable vs. stored in a function, as in the MWE below:

```julia
function new_anon()
    f(a) = a -> (a^(a-1))/a
end

test1 = new_anon()
test2(x) = new_anon()(x)

@btime test1(5) # 20.190 ns (0 allocations: 0 bytes)
@btime test2(5) # 0.001 ns (0 allocations: 0 bytes)

```

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**Author:** ![Elrod](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/elrod/32/22461_2.png) [@Elrod](https://discourse.julialang.org/u/Elrod)\
**Post date:** [March 22, 2020, 4:45pm UTC](https://discourse.julialang.org/t/speed-difference-when-storing-annonymous-function-in-variable-vs-function/36350/2 "2020-03-22T16:45:38Z")

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Because `test1` is a non-`const` global variable (while `test2` is a function).

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<div class="post-metadata">

**Author:** ![anon32405968](https://avatars.discourse-cdn.com/v4/letter/a/57b2e6/32.png) [@anon32405968](https://discourse.julialang.org/u/anon32405968)\
**Post date:** [March 22, 2020, 4:51pm UTC](https://discourse.julialang.org/t/speed-difference-when-storing-annonymous-function-in-variable-vs-function/36350/3 "2020-03-22T16:51:18Z")

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Thanks, I updated my benchmarks appropriately with the `const` prefix and they are now equal to each other.