allcator_bench result: https://github.com/SamSaffron/allocator_bench

2.3.5.md

ruby 2.3.5p376 (2017-09-14 revision 59905) [x86_64-linux]
built-in mem: 178476 duration: 5.132209188
jemalloc 3.0.0 mem: 176224 duration: 4.000590038
jemalloc 3.1.0 mem: 176228 duration: 3.905287789
jemalloc 3.2.0 mem: 181496 duration: 3.884209287
jemalloc 3.3.0 mem: 181512 duration: 3.993662677
jemalloc 3.3.1 mem: 183572 duration: 3.883753324
jemalloc 3.4.0 mem: 181564 duration: 3.92800123
jemalloc 3.4.1 mem: 181500 duration: 3.842475057
jemalloc 3.5.0 mem: 181536 duration: 3.953309345
jemalloc 3.5.1 mem: 181544 duration: 4.313772801
jemalloc 3.6.0 mem: 181508 duration: 4.028519572
jemalloc 4.0.0 mem: 210160 duration: 4.225439883
jemalloc 4.0.1 mem: 211608 duration: 3.925936574
jemalloc 4.0.2 mem: 202472 duration: 3.852219723
jemalloc 4.0.3 mem: 209808 duration: 3.851066033
jemalloc 4.0.4 mem: 211928 duration: 4.105370466
jemalloc 4.1.0 mem: 206176 duration: 4.107564367
jemalloc 4.1.1 mem: 206076 duration: 4.057138362
jemalloc 4.2.0 mem: 208032 duration: 3.92888842
jemalloc 4.2.1 mem: 206468 duration: 3.972010085
jemalloc 4.3.0 mem: 462336 duration: 7.838387476
jemalloc 4.3.1 mem: 206172 duration: 3.907296637
jemalloc 4.4.0 mem: 204736 duration: 4.12105948
jemalloc 4.5.0 mem: 204512 duration: 3.893839734
jemalloc 5.0.0 mem: 210172 duration: 3.793501218
jemalloc 5.0.1 mem: 206668 duration: 4.107995515

2.4.2.md

ruby 2.4.2p198 (2017-09-14 revision 59899) [x86_64-linux]
built-in mem: 134168 duration: 5.627236882
jemalloc 3.0.0 mem: 134564 duration: 4.128512866
jemalloc 3.1.0 mem: 134552 duration: 4.307145476
jemalloc 3.2.0 mem: 140536 duration: 4.562261136
jemalloc 3.3.0 mem: 140532 duration: 4.914138945
jemalloc 3.3.1 mem: 140616 duration: 4.265407141
jemalloc 3.4.0 mem: 140604 duration: 4.558976951
jemalloc 3.4.1 mem: 140548 duration: 4.844057985
jemalloc 3.5.0 mem: 140592 duration: 4.532079675
jemalloc 3.5.1 mem: 140528 duration: 4.603324601
jemalloc 3.6.0 mem: 140556 duration: 4.172454912
jemalloc 4.0.0 mem: 154968 duration: 4.113535398
jemalloc 4.0.1 mem: 132352 duration: 4.202243347
jemalloc 4.0.2 mem: 138548 duration: 4.422027858
jemalloc 4.0.3 mem: 132412 duration: 4.142483827
jemalloc 4.0.4 mem: 132400 duration: 4.218888027
jemalloc 4.1.0 mem: 134448 duration: 4.193291389
jemalloc 4.1.1 mem: 150916 duration: 4.143426299
jemalloc 4.2.0 mem: 156984 duration: 4.545254044
jemalloc 4.2.1 mem: 179584 duration: 4.441214336
jemalloc 4.3.0 mem: 412184 duration: 6.511175701
jemalloc 4.3.1 mem: 132472 duration: 4.124978977
jemalloc 4.4.0 mem: 132408 duration: 4.020828463
jemalloc 4.5.0 mem: 157052 duration: 4.102765889
jemalloc 5.0.0 mem: 129824 duration: 4.412487887
jemalloc 5.0.1 mem: 129232 duration: 4.322415408

2.5.0-dev

```
ruby 2.5.0dev (2017-12-08 trunk 61076) [x86_64-linux]
built-in mem: 146772 duration: 4.939828654
jemalloc 3.4.0 mem: 150840 duration: 4.197089505
jemalloc 3.4.1 mem: 150868 duration: 4.028711203
jemalloc 3.5.0 mem: 152924 duration: 3.850908897
jemalloc 3.5.1 mem: 150900 duration: 4.011525792
jemalloc 3.6.0 mem: 150860 duration: 4.066049436
jemalloc 4.0.0 mem: 126328 duration: 4.646938065
jemalloc 4.0.1 mem: 180432 duration: 4.113959835
jemalloc 4.0.2 mem: 168584 duration: 4.016996815
jemalloc 4.0.3 mem: 175488 duration: 3.90602903
jemalloc 4.0.4 mem: 180504 duration: 3.901736457
jemalloc 4.1.0 mem: 167376 duration: 3.878377173
jemalloc 4.1.1 mem: 167380 duration: 3.794761434
jemalloc 4.2.0 mem: 166872 duration: 3.928015759
jemalloc 4.2.1 mem: 171440 duration: 3.854804002
jemalloc 4.3.1 mem: 167224 duration: 3.832231584
jemalloc 4.4.0 mem: 167412 duration: 4.031140332
jemalloc 4.5.0 mem: 167408 duration: 3.856164044
jemalloc 5.0.0 mem: 189472 duration: 3.950008347
jemalloc 5.0.1 mem: 141752 duration: 4.329073964
```