Response to this post: http://stratus3d.com/blog/2019/06/29/performance-of-elixirs-access-behavior/

maps_bench.exs

# Using the benchee library

keys =
  1..12
  |> Enum.map(fn key ->
    Integer.to_string(key)
  end)

map =
  keys
  |> Enum.take_random(9)
  |> Map.new(&{&1, true})

times = 100_000

# NOTE: The benchmark loops return :ok to explicitly
# avoid generating lists as garbage (the Erlang
# compiler will turn that into a loop and avoid
# generating a list entirely).

Benchee.run(%{
  # Enable this to compare the loop overhead itself
  # "null" => fn ->
  #   for _key <- keys, _ <- 1..times, do: :ok
  #   :ok
  # end,
  "Map.get" => fn ->
    for key <- keys, _ <- 1..times do
      Map.get(map, key)
    end

    :ok
  end,
  "Access" => fn ->
    for key <- keys, _ <- 1..times do
      map[key]
    end

    :ok
  end
})

Sample results:

Name              ips        average  deviation         median         99th %
Map.get         11.19       89.37 ms     8.63%       94.00 ms      110.00 ms
Access           9.88      101.24 ms     8.40%       94.00 ms      125.00 ms

Comparison:
Map.get         11.19
Access           9.88 - 1.13x slower +11.87 ms