benchmark: trying to use benchmark.js to test performance

Test particles performance with [benchmark.js](https://github.com/bestiejs/benchmark.js)

```
1000 particles (this will give maximum ops/sec with 60 fps) x 7.82 ops/sec ±0.77% (42 runs sampled)
10000 particles x 7.69 ops/sec ±3.04% (40 runs sampled)
20000 particles x 4.49 ops/sec ±4.15% (25 runs sampled)
50000 particles x 2.03 ops/sec ±15.17% (13 runs sampled)
```