▶ ruby hash_with_indifferent_access_benchmark.rb
Calculating -------------------------------------
Common Hash#fetch access
                        47.253k i/100ms
Common Hash#[] access
                        50.406k i/100ms
HashWithIndifferentAccess#fetch Symbol
                        39.602k i/100ms
HashWithIndifferentAccess#fetch String
                        41.055k i/100ms
HashWithIndifferentAccess #[] Symbol
                        35.924k i/100ms
HashWithIndifferentAccess #[] String
                        44.995k i/100ms
Hash#with_indifferent_access #fetch Symbol
                        19.965k i/100ms
Hash#with_indifferent_access #fetch String
                        19.782k i/100ms
Hash#with_indifferent_access #[] Symbol
                        20.016k i/100ms
Hash#with_indifferent_access #[] String
                        23.079k i/100ms
-------------------------------------------------
Common Hash#fetch access
                          6.053M (±10.4%) i/s -     29.864M
Common Hash#[] access
                          8.306M (±10.1%) i/s -     40.980M
HashWithIndifferentAccess#fetch Symbol
                          1.932M (±12.8%) i/s -      9.465M
HashWithIndifferentAccess#fetch String
                          1.994M (± 7.6%) i/s -      9.935M
HashWithIndifferentAccess #[] Symbol
                          1.422M (± 5.6%) i/s -      7.113M
HashWithIndifferentAccess #[] String
                          3.804M (± 9.7%) i/s -     18.808M
Hash#with_indifferent_access #fetch Symbol
                        410.034k (± 5.4%) i/s -      2.056M
Hash#with_indifferent_access #fetch String
                        414.702k (± 6.3%) i/s -      2.077M
Hash#with_indifferent_access #[] Symbol
                        381.347k (± 5.6%) i/s -      1.902M
Hash#with_indifferent_access #[] String
                        470.877k (± 6.0%) i/s -      2.354M

Comparison:
Common Hash#[] access:  8306261.5 i/s
Common Hash#fetch access:  6053147.2 i/s - 1.37x slower
HashWithIndifferentAccess #[] String:  3803546.0 i/s - 2.18x slower
HashWithIndifferentAccess#fetch String:  1993671.6 i/s - 4.17x slower
HashWithIndifferentAccess#fetch Symbol:  1932004.0 i/s - 4.30x slower
HashWithIndifferentAccess #[] Symbol:  1422367.3 i/s - 5.84x slower
Hash#with_indifferent_access #[] String:   470876.8 i/s - 17.64x slower
Hash#with_indifferent_access #fetch String:   414701.6 i/s - 20.03x slower
Hash#with_indifferent_access #fetch Symbol:   410033.7 i/s - 20.26x slower
Hash#with_indifferent_access #[] Symbol:   381347.2 i/s - 21.78x slower