> #3 Compress Images and Videos Of course this helps, but 9 out of 10 times slowness is caused by suboptimal image sizes and/or the wrong image size is picked.

> #3 Compress Images and Videos Of course this helps, but 9 out of 10 times slowness is caused by suboptimal image sizes and/or the wrong image size is picked. Another commom problem is using background images without media queries. Think nice big full screen hero image on desktop, and that same image is served to handheld devices. Finally, WP's defaults for the img tags' sizes arg is usually off. This can be fixed if you're using Gutenberg.