Benchmarking Symbol vs Symbol#to_proc for Enumerable#inject

inject.rb

require "benchmark"
require "benchmark/ips"

array = Range.new(1,1_000_000).to_a

Benchmark.bmbm do |x|
  x.report("#inject &:*") { array.inject &:* }
  x.report("#inject :*")  { array.inject :* }
end

# Rehearsal -----------------------------------------------
# #inject &:+   0.150000   0.000000   0.150000 (  0.170740)
# #inject :+    0.110000   0.000000   0.110000 (  0.118186)
# -------------------------------------- total: 0.260000sec

#                   user     system      total        real
# #inject &:+   0.140000   0.000000   0.140000 (  0.172540)
# #inject :+    0.100000   0.000000   0.100000 (  0.114036)
# [Finished in 5.2s]