gistfile1.rb

require 'rubygems'
 
gem 'multi_json'
gem 'json'
gem 'oj'
gem 'yajl-ruby'
 
require 'benchmark'
require 'multi_json'
require 'json'
require 'oj'
require 'yajl'
 
json = '{"abc":"def"}'
 
n = 50000
Benchmark.bm(17) do |x|
  x.report("multi/json") do
    MultiJson.use(:json_pure)
    n.times { MultiJson.load(json) }
  end
  x.report("json") { n.times { JSON::parse(json) } }

  x.report("multi/oj") do
    MultiJson.use(:oj)
    n.times { MultiJson.load(json) }
  end
  x.report("oj") { n.times { Oj::Doc.parse(json) } }

  x.report("multi/yajl") do
    MultiJson.use(:yajl)
    n.times { MultiJson.load(json) }
  end
  x.report("yajl") do
    n.times { Yajl::Parser.new.parse(json) }
  end
end

object = {abc: 'def'}
Benchmark.bm(17) do |x|
  x.report("multi/json") do
    MultiJson.use(:json_pure)
    n.times { MultiJson.dump(object) }
  end
  x.report("json") { n.times { JSON(json) } }

  x.report("multi/oj") do
    MultiJson.use(:oj)
    n.times { MultiJson.dump(object) }
  end
  x.report("oj") { n.times { Oj.dump(json) } }

  x.report("multi/yajl") do
    MultiJson.use(:yajl)
    n.times { MultiJson.dump(json) }
  end

  x.report("yajl") do
    n.times { Yajl::Encoder.encode(json) }
  end
end

gistfile2.txt

                        user     system      total        real
multi/json          0.570000   0.010000   0.580000 (  0.591576)
json                0.170000   0.020000   0.190000 (  0.178378)
multi/oj            0.440000   0.010000   0.450000 (  0.456493)
oj                  0.210000   0.060000   0.270000 (  0.268035)
multi/yajl          0.530000   0.030000   0.560000 (  0.555605)
yajl                0.190000   0.040000   0.230000 (  0.228279)
                        user     system      total        real
multi/json          0.550000   0.010000   0.560000 (  0.562655)
json                0.190000   0.010000   0.200000 (  0.196212)
multi/oj            0.410000   0.000000   0.410000 (  0.411601)
oj                  0.000000   0.000000   0.000000 (  0.007718)
multi/yajl          0.520000   0.020000   0.540000 (  0.530797)
yajl                0.180000   0.020000   0.200000 (  0.201096)

my benchmark on i5-8250U, running Linux ceclinux-pc 4.9.77-1-MANJARO #1 SMP PREEMPT Wed Jan 17 23:04:54 UTC 2018 x86_64 GNU/Linux

Running via Spring preloader in process 23118
                        user     system      total        real
multi/json          0.240000   0.010000   0.250000 (  0.250096)
json                0.110000   0.000000   0.110000 (  0.113757)
multi/oj            0.220000   0.000000   0.220000 (  0.216726)
oj                  0.170000   0.060000   0.230000 (  0.230328)
multi/yajl          2.060000   0.010000   2.070000 (  2.063019)
yajl                0.110000   0.010000   0.120000 (  0.124362)
                        user     system      total        real
multi/json          0.590000   0.000000   0.590000 (  0.596703)
json                0.180000   0.000000   0.180000 (  0.176591)
multi/oj            0.170000   0.000000   0.170000 (  0.168770)
oj                  0.010000   0.010000   0.020000 (  0.008189)
multi/yajl          0.180000   0.000000   0.180000 (  0.186003)
yajl                0.100000   0.000000   0.100000 (  0.095512)