Merging Hases in Ruby 2.7.1p83

gistfile1.rb

require 'benchmark'

a = {foo: 'Hello'}
b = {bar: ' world'}

n = 100_000_000
Benchmark.bm do |x|
  x.report("{**a,**b}") do
    n.times {
      {**a, **b}
    }
  end
  x.report("{}.merge(a,b)") do
    n.times {
      {}.merge(a,b)
    }
  end
  x.report("{}.merge(**a,**b)") do
    n.times {
      {}.merge(**a,**b)
    }
  end
  x.report("{}.merge!(a,b)") do
    n.times {
      {}.merge!(a,b)
    }
  end
  x.report("{}.update(a,b)") do
    n.times {
      {}.update(a,b)
    }
  end
  x.report("[*a,*b].to_h") do
    n.times {
      [*a,*b].to_h
    }
  end
end

# Results
# {**a,**b}          18.499090   0.000953  18.500043 ( 18.535218)
# {}.merge(a,b)      17.367425   0.000000  17.367425 ( 17.396814)
# {}.merge(**a,**b)  31.909342   0.000000  31.909342 ( 31.962684)
# {}.merge!(a,b)     14.842274   0.000000  14.842274 ( 14.867258)
# {}.update(a,b)     14.798517   0.000000  14.798517 ( 14.821953)
# [*a,*b].to_h       52.512334   0.000000  52.512334 ( 52.600762)