each_with_object_each vs tap+each vs tap+update

benchmark.rb

require 'benchmark/ips'
                                                                                                                           
Benchmark.ips do |x|
                                                                                                                           
 x.report 'tap' do
   {}.tap { |results| each { |bucket| bucket.ids_by_type.each{ |type,ids| (results[type]||=[]); results[type] += ids } } }
 end
                                                                                                                           
 x.report 'each_with_object' do
   flat_map(&:ids_by_type).each_with_object({}) do |results, ids_by_type|
     results.each do |type, ids|
       ids_by_type[type] ||= []
                                                                                                                           
       ids_by_type[type] += ids
     end
   end
 end
                                                                                                                           
 x.report 'update' do
   {}.tap do |result_ids|
     flat_map(&:ids_by_type).each do |ids_by_type|
       result_ids.merge!(ids_by_type) { |_, previous_ids, next_ids| previous_ids | next_ids }
     end
   end
 end
                                                                                                                           
  x.compare!
end

result.txt

Calculating -------------------------------------
                 tap    16.692k i/100ms
    each_with_object    14.559k i/100ms
              update    17.104k i/100ms
-------------------------------------------------
                 tap    457.661k (±13.0%) i/s -      2.253M
    each_with_object    411.019k (±14.2%) i/s -      2.024M
              update    522.843k (±14.3%) i/s -      2.566M

Comparison:
              update:   522843.5 i/s
                 tap:   457660.5 i/s - 1.14x slower
    each_with_object:   411018.8 i/s - 1.27x slower