gistfile1.rb

require "benchmark/ips"

email = nil

Benchmark.ips do |x|
  x.report('com if') { email.downcase.strip if email }
  x.report('sem if') { email.to_s.downcase.strip }
end

gistfile2.txt

Calculating -------------------------------------
              com if     75866 i/100ms
              sem if     56268 i/100ms
-------------------------------------------------
              com if  7040009.2 (±18.0%) i/s -   33381040 in   5.003623s
              sem if  1728021.7 (±20.0%) i/s -    8046324 in   5.000922s