Debugging performance

Enter the dev tools and check out the Lighthouse tab. This is essentially a series of tests that analyses the currently open website on a bunch of metrics related to performance, page speed, accessibility, etc. Feel free to run the tests by clicking the Analyze Page Load button (you might want to do this in an incognito tab to avoid errors arising from extensions you're using). Once you have the results, take your time and read through them (and do click through to the reference pages mentioned alongside each test result to know more about it!)