test_benchmark.rb

require 'benchmark/ips'

Benchmark.ips do |x|
  x.report('#exists?') { User.where(id: 1).exists? }
  x.report('#any?') { User.where(id: 1).any? }
  x.report('#present?') { User.where(id: 1).present? }

  x.compare!
end

# Warming up --------------------------------------
#             #exists?   114.000  i/100ms
#                #any?   148.000  i/100ms
#            #present?   150.000  i/100ms
# Calculating -------------------------------------
#             #exists?      1.839k (± 3.2%) i/s -      9.234k in   5.026604s
#                #any?      1.296k (±32.5%) i/s -      6.068k in   5.130723s
#            #present?      1.595k (± 3.6%) i/s -      8.100k in   5.085038s
#
# Comparison:
#             #exists?:     1839.0 i/s
#            #present?:     1595.1 i/s - 1.15x  slower
#                #any?:     1296.5 i/s - 1.42x  slower