Speed

We now have lazy-loaded images by default in WordPress. This means that images wait to load until they’re just about to scroll into view – which in turn makes posts and pages feel faster as the page only needs to load what you need just before you need it. So if it’s an image-heavy post you don’t need to wait for all the images to load first, you just need to wait for the first couple of images to load.

A second benefit is that on mobile, lazy loading can also keep browsers from loading files meant for other devices – this will save on your data and help preserve battery life.

Search

You no longer need to rely on 3rd party plug-ins to deal with creating XMP sitemaps. These sitemaps basically are a list of all the URLs (pages) present on your website and allows search engines to quickly crawl all your pages – or not, depending on what pages you want to appear on search engines. In WordPress 5.5 now, by default, includes an XML sitemap.

Security

Hurrah, you can now you can choose to update your plugins and themes automatically–or even customise this process and keep the biggies like WooCommerce for a manual update so you can make sure they are compatible–all from your dashboard. Additionally, you can also now manually update plugins and themes by using a .zip file.

Additionally

On top of the 3 big S’s, there are also improvements to the block editor.

Block patterns

The new block patterns will make it simple to put together your page layouts, by showing you pre-configured layouts to select from by using the new block directly built right into the block editor.

Inline image editing

Edit images right in the block editor… crop, rotate, and zoom your photos.