Run results for: Concat vs push(...) for large arrays (100000 up to 5000000)

Test name	Executions per second
✓ Spread	1,960 Ops/sec
Apply	1,922 Ops/sec

Script Preparation code:

window.top.tests = {control:[], concat:[], spread:[], apply: []};
window.test = (new Array(100000)).fill(null).map((e, i) => ( {
    "_id": "6756f95de1bf2a3657bf2262",
    "index": 0,
    "guid": "bdc23f10-a1ac-47ad-a423-1c498f5d7857",
    "isActive": true,
    "balance": "$2,288.04",
    "picture": "http://placehold.it/32x32",
    "age": i,
    "eyeColor": "brown",
    "name": "Reid Holden",
    "gender": "male",
    "company": "KAGGLE",
    "email": "reidholden@kaggle.com",
    "phone": "+1 (844) 427-3173",
    "address": "923 Dewitt Avenue, Macdona, Florida, 2333",
    "about": "Eu quis amet ipsum id occaecat reprehenderit cillum cupidatat ullamco ad duis. Lorem tempor incididunt culpa dolor labore et officia nulla aliqua et incididunt amet dolor reprehenderit. Ut voluptate est elit quis fugiat ex magna irure eiusmod esse duis sint qui. Exercitation duis duis ullamco est eiusmod sunt eiusmod velit laboris ex elit.\r\n",
    "registered": "2017-07-12T07:52:14 -02:00",
    "latitude": 49.456753,
    "longitude": -37.824429,
    "tags": [
      "est",
      "laborum",
      "laborum",
      "incididunt",
      "adipisicing",
      "anim",
      "sit"
    ],
    "friends": [
      {
        "id": 0,
        "name": "Gutierrez Collins"
      },
      {
        "id": 1,
        "name": "Lisa Richardson"
      },
      {
        "id": 2,
        "name": "Wilson Kane"
      }
    ],
    "greeting": "Hello, Reid Holden! You have 4 unread messages.",
    "favoriteFruit": "strawberry"
  }));

window.cutoff = 50000;

Tests:

Spread
window.top.tests.spread.push(...window.test); if (window.top.tests.spread.length > window.cutoff) { window.top.tests.spread = []; console.log('reset spread'); }
Apply
window.top.tests.apply.push.apply(window.top.tests.apply, window.test); if (window.top.tests.apply.length > window.cutoff) { window.top.tests.apply = []; console.log('reset apply'); }

Run results for: Concat vs push(...) for large arrays (100000 up to 5000000)

Comparing the various ways to append to a large array

Spread

Apply