No memory leaks detected but big change of memory usage (and speed) between Node 6 & Node 8.

Node 9:

> yarn start --native
Node version: v9.4.0
1: 91.16 M / 122.5 M
2: 92.9 M / 118.31 M
3: 85.61 M / 127.75 M
4: 93.04 M / 117.26 M
5: 86.6 M / 116.21 M
6: 92.9 M / 118.31 M
7: 85.38 M / 122.5 M
8: 92.82 M / 118.31 M
9: 85.58 M / 127.75 M
10: 92.54 M / 117.26 M
11: 85.49 M / 120.93 M
12: 93.8 M / 119.36 M
13: 86.45 M / 121.98 M
14: 93.71 M / 119.36 M
15: 94.85 M / 124.6 M
16: 87.52 M / 121.98 M
17: 94.52 M / 121.45 M
18: 156.09 M / 202.72 M
19: 88.54 M / 118.83 M
20: 95.08 M / 118.83 M
Benchmark took 10.481 seconds

Node 8:

> yarn start --native
Node version: v8.9.4
1: 93.7 M / 128.82 M
2: 95.01 M / 127.25 M
3: 87.38 M / 131.44 M
4: 177.61 M / 218.47 M
5: 95.15 M / 118.86 M
6: 87.63 M / 130.92 M
7: 177.57 M / 218.47 M
8: 95.69 M / 127.25 M
9: 88.47 M / 130.39 M
10: 177.44 M / 218.47 M
11: 96.66 M / 127.25 M
12: 89.37 M / 130.92 M
13: 177.29 M / 217.95 M
14: 96.62 M / 127.25 M
15: 89.49 M / 130.92 M
16: 177.2 M / 217.42 M
17: 95.15 M / 127.77 M
18: 87.8 M / 130.92 M
19: 177.54 M / 217.95 M
20: 95.61 M / 127.77 M
Benchmark took 10.375 seconds

Node 6:

> yarn start --native
Node version: v6.12.3
1: 198.38 M / 227.57 M
2: 383.31 M / 415.27 M
3: 568.18 M / 604.01 M
4: 190.5 M / 228.62 M
5: 197.22 M / 227.57 M
6: 382.25 M / 416.32 M
7: 203.7 M / 227.57 M
8: 376.31 M / 417.37 M
9: 195.12 M / 228.62 M
10: 197.28 M / 227.57 M
11: 382.36 M / 416.32 M
12: 203.96 M / 227.57 M
13: 376.56 M / 417.37 M
14: 562.88 M / 606.11 M
15: 193.77 M / 228.62 M
16: 201.77 M / 227.57 M
17: 385.98 M / 415.27 M
18: 570.24 M / 602.96 M
19: 193.04 M / 228.62 M
20: 202.16 M / 227.57 M
Benchmark took 53.803 seconds

Node 4:

> yarn start --native
Node version: v4.8.7
1: 377.18 M / 400.37 M
2: 737.25 M / 761.54 M
3: 373.16 M / 401.4 M
4: 370.07 M / 401.4 M
5: 380.06 M / 399.34 M
6: 375.38 M / 400.37 M
7: 372.58 M / 401.4 M
8: 734.06 M / 762.58 M
9: 369.9 M / 401.4 M
10: 371.82 M / 401.4 M
11: 733.65 M / 763.61 M
12: 379.84 M / 400.37 M
13: 375.09 M / 401.4 M
14: 735.79 M / 762.58 M
15: 371.67 M / 401.4 M
16: 375.01 M / 432.36 M
17: 735.93 M / 763.61 M
18: 377.82 M / 400.37 M
19: 737.57 M / 761.54 M
20: 376.43 M / 401.4 M
Benchmark took 58.723 seconds