es_update.rb

require 'benchmark/ips'

Benchmark.ips do |x|
  x.report("update_gem_downloads") do
    updates_by_gem = {31141=>81, 55109=>36, 75586=>72, 27046=>72, 78002=>24, 80114=>62, 88344=>43, 91314=>40, 112811=>78, 74471=>3, 37936=>83, 85831=>32, 19193=>73, 106461=>26, 92080=>84, 23033=>23, 28444=>32, 69808=>25, 111504=>30, 114083=>87}
    GemDownload.update_gem_downloads(updates_by_gem)
  end

  x.report("update_gem_downloads_old") do
    updates_by_gem = {45908=>91, 80612=>46, 59193=>29, 72913=>65, 25443=>82, 59819=>60, 85201=>42, 42041=>67, 51804=>34, 43622=>86, 64017=>52, 41448=>6, 108872=>24, 28863=>15, 54962=>51, 74408=>71, 70542=>9, 27849=>5, 97372=>0, 34692=>55}
    GemDownload.update_gem_downloads_old(updates_by_gem)
  end

  x.compare!
end

report.txt

Warming up --------------------------------------
update_gem_downloads     1.000  i/100ms
update_gem_downloads_old
                         1.000  i/100ms
Calculating -------------------------------------
update_gem_downloads      2.329  (± 0.0%) i/s -     12.000  in   5.163686s
update_gem_downloads_old
                          2.255  (± 0.0%) i/s -     12.000  in   5.382416s

Comparison:
update_gem_downloads:        2.3 i/s
update_gem_downloads_old:        2.3 i/s - 1.03x  slower