json_small_bench.rb

require 'benchmark/ips'
require 'oj'
require 'json'

puts "Ruby version: #{RUBY_VERSION}"
puts "Oj version: #{Oj::VERSION}"
puts "JSON version: #{JSON::VERSION}"

json_encoder = JSON::State.new(JSON.dump_default_options)
# Sample data to hash - using varied data types
test_data = [1, "string", { a: 1, b: 2 }, [3, 4, 5]]

Oj.default_options = Oj.default_options.merge(mode: :compat)

Benchmark.ips do |x|
  x.config(time: 5, warmup: 2)

  x.report("Oj") do
    Oj.dump(test_data)
  end

  x.report("JSON reuse") do
    json_encoder.generate(test_data)
  end

  x.report("JSON") do
    JSON.dump(test_data)
  end

  x.compare!(order: :baseline)
end

results.txt

$ ruby --yjit /tmp/foo.rb
Ruby version: 3.3.4
Oj version: 3.16.6
JSON version: 2.7.3
ruby 3.3.4 (2024-07-09 revision be1089c8ec) +YJIT [arm64-darwin23]
Warming up --------------------------------------
                  Oj   535.182k i/100ms
          JSON reuse   447.109k i/100ms
                JSON   249.109k i/100ms
Calculating -------------------------------------
                  Oj      5.792M (± 0.5%) i/s  (172.64 ns/i) -     29.435M in   5.081754s
          JSON reuse      4.793M (± 1.3%) i/s  (208.65 ns/i) -     24.144M in   5.038591s
                JSON      2.676M (± 1.0%) i/s  (373.74 ns/i) -     13.452M in   5.027962s

Comparison:
                  Oj:  5792440.1 i/s
          JSON reuse:  4792621.8 i/s - 1.21x  slower
                JSON:  2675676.3 i/s - 2.16x  slower