1. Optimize Your Database
Your MySQL database tables should be cleaned regularly. These tables are sure to have some clutter in time and this has a direct impact on the load times of your WP site. Rather than use plugins to do this, getting a hands-on idea of what is going on with your database is most recommended.
Using the phpMyAdmin panel, choose the “Check All Tables Having Overhead” to get an overview of all the tables that need to be optimized. From the drop down menu, select “optimize table” which when completed, should display a success message. In case of errors in your DB tables, select the “Repair Table” option. Always remember to backup your database before making any major optimization efforts or repairing your database tables.
If you are running WordPress 2.9 and below, which do not support automatic database optimization, add the line below to your wp-config.php file:
define (‘WP_ALLOW_REPAIR’, TRUE);
2. Cache Your Posts
Caching your WordPress posts creates .html files that are served to visitors instead of having to query the database every time, effectively speeding up your website. To do this, you can use popular WP plugins like WP Super Cache, Hyper Cache, W3 Total Cache or the DB Cache. Some plugins like the W3 Total Cache improve your server performance, caching every aspect of your site and reducing download times of site elements.
If you are caching a high traffic website, you might want to consider adding an opcode cache like Alternative PHP Cache (APC) to your server to enhance PHP’s performance. Using a CDN (content delivery network) helps to server your content via a number of servers. This is an expensive option as most CDNs are quite expensive. I would recommend a CDN like CloudFare – it is free but with features that come close to paid services.
3. Compress and Combine Your JS and CSS Files
Compressing and combining JS and CSS files has been shown to improve site loading times. Compressing reduces the overall page size while combining multiple files reduces the number of HTTP requests to the web server required to retrieve the files. There are many JS and CSS compressors out there available for free.
A much easier way would be to use the WP Minify plug-in that combines your various JS can CSS files into one file. And of course compressing images further using a plugin like WP Smush.it does not hurt.
4. Use CSS Sprites
This is a fantastic technique of combining multiple images into a single file with all the information about the graphical elements in it. Sprites can, for example, be used to on a blog’s sidebar where there are 5 buttons each requiring 5 images. These 5 different images can be combined into one file requiring only that single file to be loaded thereby speeding up the site and saving bandwidth.
I recommend a tool like “Sprite Me” to make your sprite coding job easier.
5. Clean Your House
Of course, there are other obvious ways to speed up a WP site like upgrading your WordPress installation, upgrading plugins and deleting unused plugins. These should be on your regular site maintenance list.