We now know the Google takes site speed into account when determining search rankings nowadays, just how much of an effect speed has on your placement is unknown at this point but it makes sense to optimize your site to be as fast as possible as this not only helps your search placement, it will improve your site visitors experience and can make the difference between a sale or referral for you or one for a competitors site which loads faster. This becomes even more important as we are in the age of mobile browsing - people just wont wait for your site to load when they can hit the back button and get the info required elsewhere.
The starting point of speeding up your site is to make sure you have a fast-loading WordPress theme from the start, there are many factors which can slow your site down such as loading scripts and styles, sliders, web fonts and other external sources can all add a delay to your site loading. A new service, named WPSpeedster, which launched the other week aims to help you find the fastest loading themes in the WordPress directory.
WPSpeedster has a website where they have tested over 2500 themes from the directory for speed, using Google PageSpeed. All themes are tested on desktop and mobile for homepage speed and post page loading times and are then given a ranking.
Listed on the homepage you will find the top ranked themes by Overall (Mobile+Desktop), Top Scorers for Home page/Desktop, Top Scorers for Home page/Mobile , Top Scorers for Post page/Desktop and Top Scorers for Post page/Mobile.
The current top theme ranked is "Montezuma" which has a score of 98 overall, each theme has it's own page you can click through to for more details about it such as the description, tags, preview and download links :
The site also has a "Fastest Wordpress themes Overall" page which lists the top 50 themes and lets you browse through seeing all the themes ranked in order of speed.
Free Speed Test Plugin
There is a free plugin available to download from the directory, which you can add to your site to help you by showing the page speed results when testing out new themes.
Once you have installed the plugin, you will see a new menu item named "Themes Speed Test" which lists your available themes and will show speed scores for them if they are in the directory.
At the top you can search for specific themes and click through to view the top scorers.
If you are looking for a new theme to use from the directory then taking a minute to use WPSpeedster could help you make your decision on which theme to use - its a useful tool and it would even be handy to see this information built-in to the theme directory itself. I would like to see it expanded to include commercial themes as well, it could start off with some of the more popular themes, I'd like to see the data on some of the recent trend of "kitchen-sink" type multipurpose themes and see how they fare against each other.