gistfile1.rb

require 'benchmark'

def method1(&block)
  true if block
end

def method2(&block)
  true if block_given?
end

n = 10_000_000
Benchmark.bm do |x|
  x.report { n.times { method1 {} } }
  x.report { n.times { method2 {} } }
end

#     user     system      total        real
# 4.780000   0.020000   4.800000 (  4.792239)
# 5.260000   0.000000   5.260000 (  5.260888)