Depending on the theme and the plugins that are used, there can be a lot of extra coding added to a website and it takes extra time to process this information.

Most people simply “Deactivate” plugins instead of Deleting them. The problem with this is that some of the coding is left behind which adds to your load time.

Not all of the WordPress Themes are programmed by experts so sometimes you’re going to be using a theme that causing some confusion to the servers when it is being processed.

The images that show up later down the page are known as Offscreen images. By default, all of the images are loaded immediately when the page is requested and this can take some extra time depending on how many images there are. Using a Lazy Load option will defer those images from being loaded until the user needs to see them.

Having externalized javascript and CSS is not always a bad thing. The main downside is that when there is a new visitor, all of that information has to be called and brought back to the page. By inlining Javascript and CSS, it can decrease load time.

If a website is on shared hosting, it may have a slower load time because resources are being shared by other websites. Finding a server that id dedicated or that is WordPress friendly can help speed up websites.