Help/About: Update performance content and images

src/wp-admin/about.php

@@ -138,7 +138,7 @@
 					</svg>
 				</div>
 				<h3><?php _e( 'Performance updates' ); ?></h3>
-				<p><?php _e( 'WordPress 6.9 includes a broad set of performance updates, including a faster way of browsing and selecting styles, optimizations of the navigation link, fixes the layout shifts caused by the Video block, quicker load of the terms selector, no extra network request for retrieving feature media, and optimization in the Editor.' ); ?></p>
+				<p><?php _e( 'WordPress 6.9 includes a broad set of performance enhancements. A better <abbr title="Largest Contentful Paint">LCP</abbr> metric is achieved through improved loading of conditional and inlined stylesheets, script loading with fetchpriority support, and additional core optimizations. Editor advances include fixes for layout shifts caused by the Video block and faster loading of the terms selector.' ); ?></p>
 			</div>
 			<div class="column">
 				<div class="about__image">