String interpolation

/bin/bash -c "/Users/thunder/.rvm/bin/rvm ruby-2.3.7@mejuri do /Users/thunder/.rvm/rubies/ruby-2.3.7/bin/ruby '/Users/thunder/Library/Application Support/JetBrains/RubyMine2020.2/scratches/scratch.rb'"

Warming up --------------------------------------
Direct interpolation   426.585k i/100ms
Percent interpolation
                       232.103k i/100ms
  Plus concatenation   507.047k i/100ms
Calculating -------------------------------------
Direct interpolation      4.393M (± 0.3%) i/s -     43.938M in  10.005452s
Percent interpolation
                          2.302M (± 0.3%) i/s -     23.210M in  10.086796s
  Plus concatenation      5.125M (± 0.4%) i/s -     51.212M in  10.000257s
                   with 95.0% confidence

Comparison:
  Plus concatenation:  5124894.8 i/s
Direct interpolation:  4392761.8 i/s - 1.17x  (± 0.01) slower
Percent interpolation:  2301505.3 i/s - 2.23x  (± 0.01) slower
                   with 95.0% confidence
                   
-----------------------------------------------------------------------------
/bin/bash -c "/Users/thunder/.rvm/bin/rvm ruby-2.4.9 do /Users/thunder/.rvm/rubies/ruby-2.4.9/bin/ruby '/Users/thunder/Library/Application Support/JetBrains/RubyMine2020.2/scratches/scratch.rb'"

Warming up --------------------------------------
Direct interpolation   448.798k i/100ms
Percent interpolation
                       233.322k i/100ms
  Plus concatenation   462.810k i/100ms
Calculating -------------------------------------
Direct interpolation      4.466M (± 0.2%) i/s -     44.880M in  10.050223s
Percent interpolation
                          2.371M (± 0.5%) i/s -     23.799M in  10.047935s
  Plus concatenation      5.051M (± 1.0%) i/s -     50.446M in  10.019332s
                   with 95.0% confidence

Comparison:
  Plus concatenation:  5051188.0 i/s
Direct interpolation:  4465979.8 i/s - 1.13x  (± 0.01) slower
Percent interpolation:  2370744.8 i/s - 2.13x  (± 0.02) slower
                   with 95.0% confidence
--------------------------------------------------------------------------
/bin/bash -c "/Users/thunder/.rvm/bin/rvm ruby-2.5.8 do /Users/thunder/.rvm/rubies/ruby-2.5.8/bin/ruby '/Users/thunder/Library/Application Support/JetBrains/RubyMine2020.2/scratches/scratch.rb'"

Warming up --------------------------------------
Direct interpolation   471.397k i/100ms
Percent interpolation
                       236.414k i/100ms
  Plus concatenation   468.578k i/100ms
Calculating -------------------------------------
Direct interpolation      4.646M (± 0.2%) i/s -     46.668M in  10.045768s
Percent interpolation
                          2.316M (± 0.3%) i/s -     23.169M in  10.006941s
  Plus concatenation      4.570M (± 0.6%) i/s -     45.921M in  10.062382s
                   with 95.0% confidence

Comparison:
Direct interpolation:  4645824.9 i/s
  Plus concatenation:  4570170.5 i/s - 1.02x  (± 0.01) slower
Percent interpolation:  2316002.5 i/s - 2.01x  (± 0.01) slower
                   with 95.0% confidence
----------------------------------------------------------------------------

/bin/bash -c "/Users/thunder/.rvm/bin/rvm ruby-2.6.6 do /Users/thunder/.rvm/rubies/ruby-2.6.6/bin/ruby '/Users/thunder/Library/Application Support/JetBrains/RubyMine2020.2/scratches/scratch.rb'"

Warming up --------------------------------------
Direct interpolation   509.128k i/100ms
Percent interpolation
                       256.033k i/100ms
  Plus concatenation   549.347k i/100ms
Calculating -------------------------------------
Direct interpolation      4.917M (± 0.3%) i/s -     49.385M in  10.045288s
Percent interpolation
                          2.489M (± 1.0%) i/s -     24.835M in  10.009935s
  Plus concatenation      5.350M (± 0.5%) i/s -     53.836M in  10.070162s
                   with 95.0% confidence

Comparison:
  Plus concatenation:  5349932.8 i/s
Direct interpolation:  4917308.6 i/s - 1.09x  (± 0.01) slower
Percent interpolation:  2489130.0 i/s - 2.15x  (± 0.02) slower
                   with 95.0% confidence
---------------------------------------------------------------
Code:

# frozen_string_literal: true

# Install the necessary gems:
# gem install benchmark-ips
# gem install kalibera

# gem install benchmark-ips
# gem install kalibera

require 'benchmark/ips'
require 'active_support'

# Enable and start GC before each job run. Disable GC afterwards.
#
# Inspired by https://www.omniref.com/ruby/2.2.1/symbols/Benchmark/bm?#annotation=4095926&line=182
class GCSuite
  def warming(*)
    run_gc
  end

  def running(*)
    run_gc
  end

  def warmup_stats(*)
  end

  def add_report(*)
  end

  private

  def run_gc
    GC.enable
    GC.start
    GC.disable
  end
end

suite = GCSuite.new

n = 1
s1 = "Test #{n} string"
s2 = 'Test %s string' % n
s3 = 'Test ' + n.to_s + ' string'

Benchmark.ips do |x|
  x.config(time: 10, warmup: 5, stats: :bootstrap, confidence: 95)

  x.report('Direct interpolation') do
    "Test #{n} string"
  end

  x.report('Percent interpolation') do
    'Test %s string' % n
  end

  x.report('Plus concatenation') do
    'Test ' + n.to_s + ' string'
  end

  x.compare!
end