perf.js

function name1() {
    return 1
}

const name2 = new Function(`return function name2() {
    return 1
}`)()

let start1 = 0, end1 = 0;
let start2 = 0, end2 = 0;

for (let i = 0; i < 9999; i++) {
    console.error(name1())
    console.error(name2())
}

start1 = Date.now()
for (let i1 = 0; i1 < 9999; i1++) {
    console.error(name1())
}
end1 = Date.now()

start2 = Date.now()
for (let i2 = 0; i2 < 9999; i2++) {
    console.error(name2())
}
end2 = Date.now()

console.log(end1 - start1, 'ms')
console.log(end2 - start2, 'ms')