Add quick benchmark

[ardecvz]

Result:

Using sqlite3
Run options: --seed 1477

# Running:

Warming up --------------------------------------
                Code    51.000  i/100ms
            Baseline    55.000  i/100ms
Calculating -------------------------------------
                Code    485.488  (± 4.7%) i/s -      4.845k in  10.002550s
            Baseline    512.926  (± 3.3%) i/s -      5.170k in  10.090562s

Comparison:
            Baseline:      512.9 i/s
                Code:      485.5 i/s - same-ish: difference falls within error

F

Failure:
AssociationsPerformanceTest#test_performance_tree_code_only [/home/ardecvz/dev/rails/activerecord/test/cases/associations/performance_test.rb:47]:
Expecting 1.05 times slower at most, but got 1.0565176525729307 times slower


bin/test test/cases/associations/performance_test.rb:37

Warming up --------------------------------------
                Code    37.000  i/100ms
            Baseline    55.000  i/100ms
Calculating -------------------------------------
                Code    396.518  (± 3.0%) i/s -      3.996k in  10.086650s
            Baseline    496.981  (± 6.0%) i/s -      5.005k in  10.110700s

Comparison:
            Baseline:      497.0 i/s
                Code:      396.5 i/s - 1.25x  (± 0.00) slower

F

Failure:
AssociationsPerformanceTest#test_performance_objects_allocating [/home/ardecvz/dev/rails/activerecord/test/cases/associations/performance_test.rb:67]:
Expecting 1.2 times slower at most, but got 1.2533632086343738 times slower


bin/test test/cases/associations/performance_test.rb:57



Finished in 48.031965s, 0.0416 runs/s, 0.0416 assertions/s.
2 runs, 2 assertions, 2 failures, 0 errors, 0 skips

Win case:

Using sqlite3
Run options: --seed 59797

# Running:

Warming up --------------------------------------
                Code   195.000  i/100ms
            Baseline   133.000  i/100ms
Calculating -------------------------------------
                Code      1.969k (± 5.5%) i/s -     19.695k in  10.033527s
            Baseline      1.386k (± 2.7%) i/s -     13.965k in  10.086623s

Comparison:
                Code:     1969.3 i/s
            Baseline:     1385.6 i/s - 1.42x  (± 0.00) slower

F

Failure:
AssociationsPerformanceTest#test_performance_sql_only [/home/ardecvz/dev/rails/activerecord/test/cases/associations/performance_test.rb:87]:
Expecting 0.7 times slower at most, but got 0.7035809515047433 times slower


bin/test test/cases/associations/performance_test.rb:77



Finished in 25.678418s, 0.0389 runs/s, 0.0389 assertions/s.
1 runs, 1 assertions, 1 failures, 0 errors, 0 skips