const paren = document.createElement('div');

let n = 0;

let str= "";

while(true) {

    n++;

    str += '<div><p class="font-bold">Hello!</p></div>';

    if(n===100000) 

        break;

}

paren.innerHTML = str;

const paren = document.createElement('div');

let n = 0;

    const div = document.createElement('div');

    const p = document.createElement('p');

    p.classList.add('font-bold');

    p.textContent = 'Hello!';

    div.appendChild(p);

while(true) {

    n++;

    paren.appendChild(div.cloneNode(true));

    if(n===100000) 

        break;

}