date-format-performance.js

const moment = require('moment')
const dayjs = require('dayjs')
const { format } = require('date-fns')

const limit = 10000

const date = new Date()

console.time('intl')
for (let i = 0; i < limit; i++) {
  new Intl.DateTimeFormat('jp', {
    year: 'numeric',
    month: 'numeric',
    day: 'numeric',
    hour: 'numeric',
    minute: 'numeric',
    second: 'numeric',
    hour12: false
  }).format(date)
}
console.timeEnd('intl')

console.time('moment')
for (let i = 0; i < limit; i++) {
  moment(date).format('YYYY-M-DD H:mm:ss')
}
console.timeEnd('moment')

console.time('dayjs')
for (let i = 0; i < limit; i++) {
  dayjs(date).format('YYYY-M-DD H:mm:ss')
}
console.timeEnd('dayjs')

console.time('date-fns')
for (let i = 0; i < limit; i++) {
  format(date, 'yyyy-M-dd H:mm:ss')
}
console.timeEnd('date-fns')

date-format-performance2.js

const moment = require('moment')
const dayjs = require('dayjs')
const { format } = require('date-fns')

const limit = 10000

const date = new Date()

console.time('intl')
const intl = new Intl.DateTimeFormat('jp', {
  year: 'numeric',
  month: 'numeric',
  day: 'numeric',
  hour: 'numeric',
  minute: 'numeric',
  second: 'numeric',
  hour12: false
})
for (let i = 0; i < limit; i++) {
  intl.format(date)
}
console.timeEnd('intl')

console.time('moment')
for (let i = 0; i < limit; i++) {
  moment(date).format('YYYY-M-DD H:mm:ss')
}
console.timeEnd('moment')

console.time('dayjs')
for (let i = 0; i < limit; i++) {
  dayjs(date).format('YYYY-M-DD H:mm:ss')
}
console.timeEnd('dayjs')

console.time('date-fns')
for (let i = 0; i < limit; i++) {
  format(date, 'yyyy-M-dd H:mm:ss')
}
console.timeEnd('date-fns')

test.md

$ node -v
v12.8.1

$ node date-performance.js
intl: 3407.266ms
moment: 185.616ms
dayjs: 205.384ms
date-fns: 220.086ms

test2.md

$ node -v
v12.8.1

$ node date-performance2.js
intl: 132.686ms
moment: 219.558ms
dayjs: 183.621ms
date-fns: 181.078ms