# Performance of functions with keyword arguments

**URL:** https://discourse.julialang.org/t/performance-of-functions-with-keyword-arguments/5916
**Category:** General Usage
**Created:** [September 16, 2017, 7:53am UTC](https://discourse.julialang.org/t/performance-of-functions-with-keyword-arguments/5916 "2017-09-16T07:53:01Z")
**Posts on this page:** 1
**Showing post:** 3

<div class="post-metadata">

### Author: ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [September 16, 2017, 9:54am UTC](https://discourse.julialang.org/t/performance-of-functions-with-keyword-arguments/5916/3 "2017-09-16T09:54:53Z")

</div>

Perhaps:

```julia
julia> f_kw(x; y = 3) = x + y
f_kw (generic function with 1 method)

julia> f(x, y = 3) = x + y
f (generic function with 2 methods)

julia> @btime f_kw(2);
  1.789 ns (0 allocations: 0 bytes)

julia> @btime f_kw(2, y = 3);
  66.668 ns (1 allocation: 96 bytes)

julia> @btime f(2);
  1.789 ns (0 allocations: 0 bytes)

```

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