Hide top bar on video pages ........... works but takes forever to load

// ==UserScript==
// @name         Hide top bar on video pages ........... works but takes forever to load
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Hides the top bar on YouTube video pages
// @author       Your Name
// @match        *://www.youtube.com/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // Get the top bar element
    var topBar = document.getElementById('masthead-container');

    // Check if we're on a video page
    function checkPage() {
        if (window.location.href.indexOf('/watch') > -1) {
            // If so, hide the top bar
            if (topBar) {
                topBar.style.display = 'none';
            }
        } else {
            // If we're not on a video page, show the top bar
            if (topBar) {
                topBar.style.display = 'block';
            }
        }
    }

    // Create a MutationObserver to continuously check for changes to the page
    var observer = new MutationObserver(function(mutations) {
        mutations.forEach(function(mutation) {
            if (mutation.type === 'childList') {
                checkPage();
            }
        });
    });

    // Start observing the document for changes
    observer.observe(document.body, { childList: true, subtree: true });

    // Check the page initially
    checkPage();
})();