GeezerVison

                                                                 confidence improvement accuracy (*)    (**)   (***)
events/ee-add-remove.js n=1000000 removeListener=0 newListener=0        ***     11.10 %       ±3.59%  ±4.82%  ±6.35%
events/ee-add-remove.js n=1000000 removeListener=0 newListener=1        ***     24.50 %       ±3.28%  ±4.37%  ±5.72%
events/ee-add-remove.js n=1000000 removeListener=1 newListener=0        ***      8.60 %       ±4.33%  ±5.81%  ±7.64%
events/ee-add-remove.js n=1000000 removeListener=1 newListener=1                 3.22 %       ±3.94%  ±5.25%  ±6.84%
events/ee-emit.js listeners=10 argc=0 n=2000000                         ***      6.57 %       ±1.54%  ±2.05%  ±2.66%
events/ee-emit.js listeners=10 argc=10 n=2000000                        ***      8.54 %       ±1.18%  ±1.57%  ±2.04%
events/ee-emit.js listeners=10 argc=2 n=2000000                         ***      6.27 %       ±1.37%  ±1.82%  ±2.37%
events/ee-emit.js listeners=10 argc=4 n=2000000                         ***      9.21 %       ±1.36%  ±1.81%  ±2.37%
events/ee-emit.js listeners=1 argc=0 n=2000000                          ***    146.74 %       ±7.88% ±10.54% ±13.83%
events/ee-emit.js listeners=1 argc=10 n=2000000                         ***    141.56 %       ±9.43% ±12.60% ±16.52%
events/ee-emit.js listeners=1 argc=2 n=2000000                          ***    155.60 %       ±9.92% ±13.31% ±17.55%
events/ee-emit.js listeners=1 argc=4 n=2000000                          ***    166.25 %      ±21.89% ±29.45% ±39.02%
events/ee-emit.js listeners=5 argc=0 n=2000000                          ***     13.69 %       ±3.19%  ±4.24%  ±5.52%
events/ee-emit.js listeners=5 argc=10 n=2000000                         ***      6.82 %       ±3.51%  ±4.67%  ±6.09%
events/ee-emit.js listeners=5 argc=2 n=2000000                          ***     11.49 %       ±3.55%  ±4.74%  ±6.20%
events/ee-emit.js listeners=5 argc=4 n=2000000                          ***      6.43 %       ±2.49%  ±3.31%  ±4.31%
events/ee-listener-count-on-prototype.js n=50000000                     ***     -7.27 %       ±2.11%  ±2.81%  ±3.66%
events/ee-listeners.js raw='false' listeners=50 n=5000000                       -0.75 %       ±1.79%  ±2.39%  ±3.13%
events/ee-listeners.js raw='false' listeners=5 n=5000000                        -1.80 %       ±3.50%  ±4.67%  ±6.13%
events/ee-listeners.js raw='true' listeners=50 n=5000000                  *     -2.14 %       ±2.00%  ±2.67%  ±3.48%
events/ee-listeners.js raw='true' listeners=5 n=5000000                  **     -6.56 %       ±3.94%  ±5.24%  ±6.83%
events/ee-once.js argc=0 n=20000000                                     ***     19.11 %       ±2.15%  ±2.88%  ±3.78%
events/ee-once.js argc=1 n=20000000                                     ***     19.71 %       ±2.23%  ±2.97%  ±3.88%
events/ee-once.js argc=4 n=20000000                                     ***     18.59 %       ±1.28%  ±1.71%  ±2.23%
events/ee-once.js argc=5 n=20000000                                     ***     19.69 %       ±1.70%  ±2.27%  ±2.97%
events/eventtarget.js listeners=10 n=1000000                                     0.74 %       ±5.87%  ±7.81% ±10.18%
events/eventtarget.js listeners=1 n=1000000                                     -4.58 %       ±4.94%  ±6.62%  ±8.71%
events/eventtarget.js listeners=5 n=1000000                                     -1.30 %       ±2.18%  ±2.90%  ±3.79%

Be aware that when doing many comparisons the risk of a false-positive
result increases. In this case, there are 28 comparisons, you can thus
expect the following amount of false-positive results:
  1.40 false positives, when considering a   5% risk acceptance (*, **, ***),
  0.28 false positives, when considering a   1% risk acceptance (**, ***),
  0.03 false positives, when considering a 0.1% risk acceptance (***)

'use strict';
const common = require('../common.js');
const { EventEmitter } = require('events');

const bench = common.createBenchmark(main, {
  events: [1, 2, 3, 5],
  n: [1e6],
});

function main({ events, n }) {
  const ee = new EventEmitter();
  const listeners = [];

  for (let k = 0; k < 10; k += 1)
    listeners.push(() => {});

  const eventNames = [];
  for (let k = 0; k < events; ++k)
    eventNames.push(`dummy${k}`);

  bench.start();
  for (let i = 0; i < n; i += 1) {
    for (const eventName of eventNames) {
      for (let k = listeners.length; --k >= 0; /* empty */) {
        ee.on(eventName, listeners[k]);
      }
    }
    for (const eventName of eventNames) {
      for (let k = listeners.length; --k >= 0; /* empty */) {
        ee.removeListener(eventName, listeners[k]);
      }
    }
  }
  bench.end(n);
}