Benchmark: Object spreading vs mutation in reduce

Tests:

Object spreading
[...new Array(1000)].reduce( (acc, item, index) => ({ ...acc, [index]: {} }), {}, );
Mutation
[...new Array(1000)].reduce( (acc, item, index) => { acc[index] = {}; return acc; }, {}, );

Rendered benchmark preparation results:

Previous results

Test case name	Result
Object spreading
Mutation

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Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36

Browser/OS: Chrome 76 on Windows

Test name	Executions per second
Object spreading	1602.2 Ops/sec
Mutation	45860.1 Ops/sec

Object spreading vs mutation in reduce (version: 0)