each_with_index vs each.with_index

each_with_index.rb

#!/usr/bin/env ruby
require "benchmark/ips"

# ruby 3.3.6 (2024-11-05 revision 75015d4c1f) [x86_64-linux]
# Warming up --------------------------------------
#      each.with_index     2.460k i/100ms
#      each_with_index     3.613k i/100ms
# Calculating -------------------------------------
#      each.with_index     26.436k (± 3.7%) i/s   (37.83 μs/i) -    132.840k in   5.032459s
#      each_with_index     37.158k (± 5.1%) i/s   (26.91 μs/i) -    187.876k in   5.070741s

# Comparison:
#      each_with_index:    37158.1 i/s
#      each.with_index:    26436.1 i/s - 1.41x  slower

ARRAY = [*1..100]

def each_with_index_se
  ARRAY.each.with_index do |number, index|
    number + index
  end
end

def each_with_index_si
  ARRAY.each_with_index do |number, index|
    number + index
  end
end

Benchmark.ips do |x|
  x.report("each.with_index") { each_with_index_se }
  x.report("each_with_index") { each_with_index_si }
  x.compare!
end