 Nihao, here's what's new in DevTools in Chrome 78. The Audits panel now has multi-client support, which means that you can now experiment with code changes within DevTools and then audit the page to see how those changes affect your score. My Audits panel report says that my performance score isn't very good, mainly because this page has three render blocking resources, jQuery, Lodash, and 3JS. The Learn More link tells me I should use the async or defer attribute on JavaScript that isn't needed for the page load. The problem here is that the build process for this site is slow and it'll take a long time to test out this change. So what I can do now instead is test out the changes within DevTools. First, let's just block the jQuery request because I happen to know we don't use that code anymore. I press Ctrl Shift P or Command Shift P on Mac and run the show request blocking command. Then I click add pattern, then type jQuery, then click add. To add async attributes to the other scripts, I'll press Ctrl Shift P or Command Shift P on Mac again and run the show overrides command. Then select a folder, then click allow, and now my code changes are saved to that folder. Next, I press Ctrl P or Command P on Mac and open the HTML for this page. Then add the async attribute to the Lodash and 3JS script tags and press Ctrl S or Command S on Mac to save the changes. Now when I go back to the audits panel and click perform and audit, then click run audits to audit the page again. When the audit finishes, we can see a substantial improvement in the performance score. The background services section of the application panel now supports payment handler events. The payment handler API makes it easier to collect payment information from users, which you can learn more about in this article. To debug payment handler events, first go to the application panel, then open the payment handler section, then click record. DevTools will now record payment handler activity for three days, even when DevTools is closed. For example, first I close DevTools, then trigger some payment handler activity and I work through the payment handler UI, then after a while the payment goes through. To debug the payment handler activity, I press Ctrl Shift I or Command Option I on Mac to open the application panel backup and my table is empty because I haven't enabled the show events from other domains checkbox. But once I do that, I can see payment events and I can click an event to view its details. The new third-party usage diagnostic audit tells you how much third-party code your page requested and how long that third-party code blocked the main thread while the page loaded. In the performance section of my audits report, I can see the new third-party usage audit. If I click that audit to expand it, I see which third-party domains were detected on my page, the total size of network requests coming from that domain and the amount of time that each third-party blocked the main thread. The performance panel now supports the new largest contentful paint metric. Largest contentful paint is a new metric introduced in Chrome 77 that measures when the largest content element in the viewport was rendered. Check out web.dev slash largest contentful paint to learn more about it. After recording performance, the LCP marker in the timing section tells you when your largest contentful paint event happened. If you hover over the marker, DevTools highlights the largest content element node in the viewport. Or you can click the marker, then open the summary tab and hover over related node. If you click related node, DevTools opens that node in the DOM tree. If you ever encounter a bug in DevTools or have a feature request, you can now file issues on the DevTools engineering team's tracker from the main menu. Click the main menu, then go to help, then select report a DevTools issue. Please tell us what Chrome version and operating system you're using, and please describe how to reproduce the problem. Thanks for watching.