fib_while.rb

require 'benchmark/ips'

def fib_while(n)
  a = 0
  b = 1
  while n > 0
    a, b = b, a + b
    n -= 1
  end
  a
end

def fib_times(n)
  a = 0
  b = 1
  n.times { a, b = b, a + b }
  a
end

def fib_times_nil(n)
  a = 0
  b = 1
  n.times { a, b = b, a + b; nil }
  a
end

Benchmark.ips do |x|
  x.report 'fib_while(30)' do
    fib_while(30)
  end

  x.report 'fib_times(30)' do
    fib_times(30)
  end

  x.report 'fib_times_nil(30)' do
    fib_times_nil(30)
  end
end

results.txt

ruby 3.3.0 (2023-12-25 revision 5124f9ac75) +YJIT [x86_64-linux]
Warming up --------------------------------------
       fib_while(30)   784.380k i/100ms
       fib_times(30)    44.572k i/100ms
   fib_times_nil(30)   100.193k i/100ms
Calculating -------------------------------------
       fib_while(30)      8.360M (± 0.2%) i/s  (119.62 ns/i) -     42.357M in   5.066855s
       fib_times(30)    444.412k (± 0.1%) i/s    (2.25 μs/i) -      2.229M in   5.014717s
   fib_times_nil(30)      1.018M (± 0.2%) i/s  (982.32 ns/i) -      5.110M in   5.019506s

truffleruby 24.0.1, like ruby 3.2.2, Oracle GraalVM Native [x86_64-linux]
Warming up --------------------------------------
       fib_while(30)    37.796M i/100ms
       fib_times(30)    38.008M i/100ms
   fib_times_nil(30)    38.025M i/100ms
Calculating -------------------------------------
       fib_while(30)    379.649M (± 1.0%) i/s    (2.63 ns/i) -      1.928B in   5.077866s
       fib_times(30)    379.985M (± 0.3%) i/s    (2.63 ns/i) -      1.900B in   5.001354s
   fib_times_nil(30)    379.773M (± 0.4%) i/s    (2.63 ns/i) -      1.901B in   5.006369s