reject! vs next

main.rb

require 'benchmark/ips'

N = 1_000_000
ARRAY = N.times.map { rand }

Benchmark.ips do |x|
  x.report("reject") do
    arr = ARRAY.dup
    out = []
    arr.reject! { _1 >= 0.5 }
    arr.each { out << _1 }
  end

  x.report("next") do
    arr = ARRAY.dup
    out = []
    arr.each { next if _1 >= 0.5; out << _1 }
  end
  x.hold! 'temp_results'
  x.compare!
end

result.txt

Warming up --------------------------------------
              reject     2.000  i/100ms
                next     2.000  i/100ms
Calculating -------------------------------------
              reject     20.503  (± 0.0%) i/s -    104.000  in   5.072750s
                next     25.475  (± 0.0%) i/s -    128.000  in   5.025467s

Comparison:
                next:       25.5 i/s
              reject:       20.5 i/s - 1.24x  (± 0.00) slower