Plugin Laser Loader download is very small (4,9 KiB) and fast. The plugin adds a little loading progress bar at the top of the page to indicate that the next page is loading. You could see a similar UI pattern on YouTube or Medium.
The progress bar appears as a thin line overlaying the content, sitting right underneath the browser toolbar, growing in width across the page as the next one loads. This is an interesting UI pattern to a subtle way to show load progress on a page. Improve your website interaction for users, with realistic trickle animations, tell your users that something’s happening.