bench.rb

require 'benchmark/ips'

array = %w(abc def ghi jkl)

ok  = %w(abc jkl)
bad = %w(abc yio)

Benchmark.ips do |x|
  x.report('& ok')  { (array & ok).size == ok.size }
  x.report('all ok') { ok.all? { |e| array.include?(e) } }

  x.report('& bad') { (array & bad).size == bad.size }
  x.report('all bad') { bad.all? { |e| array.include?(e) } }

  x.compare!
end

Comparison:
              all ok:  1475953.4 i/s
             all bad:  1360481.8 i/s - same-ish: difference falls within error
               & bad:  1033699.0 i/s - 1.43x  slower
                & ok:   972944.0 i/s - 1.52x  slower