bm.rb

require 'benchmark'

# Benchmarking Array#compact & Array#join
n = 1_000_000
Benchmark.bm do |x|
  x.report('3 elements + nil') { n.times { ['a', 'b', 'c', nil].compact.join('::') } }
  x.report('3 elements') { n.times { ['a', 'b', 'c'].compact.join('::') } }
end

#       user         system     total      real
# 3 elements + nil  2.170000   0.040000   2.210000 (  2.217473)
# 3 elements        1.860000   0.040000   1.900000 (  1.888981)