Some themes are faster than others, it’s true! Unfortunately, there are a lot of themes out there that have bloat. Some themes have a bunch of CSS and JavaScript that is not written in an efficient way, so that the file size is much larger than it should be. If you want to get your WP instance going as fast as possible, it will be good to choose one of the fastest themes.
We’ve tried a lot of WordPress themes, and according to our tests, here are the best free themes for both site speed and SEO:
Honorable mention: