I have managed and maintained a few WordPress sites in my time. There are a few plugins that I use personally as well as suggest to my clients and they are WP-Super Cache, WP-Minify, and Use Google Libraries. Each of the plugins play an important role in improving the overall performance of one’s site. If you use one then you should use all three because complement each other nicely. Like with a majority of the WordPress plugins available, these are free!
First off WP-Super Cache. This plug-in in particular is filled to the brim with features. WP-Super Cache gives you the option to use PHP Caching or Apache mod_rewrite caching. At the core is an extremely powerful caching system which allows for compression, mobile device support and more. As we dig deeper we also notice that WP-Super Cache supports the use of a Content Delivery Network or CDN such as Amazon S3 or others. The CDN functionality of WP-Super Cache goes great with CDN Sync for WordPress. Further on we also notice that a few “plugins” are available.
These are useful because they not only allow for the disabling of the “Awaiting Moderation” notification that is presented to the user after posting a comment but also introduces the ability to do something called domain mapping which allows for multiple domains to be mapped to a single blog. WP-Super Cache really helped Scott Beale when his site Laughing Squid experienced a major traffic spike.
Finally, Use Google Libraries. This plugin is nice because it allows WordPress to use the AJAX API served up by Google’s CDN rather than the serving it up locally. This not only ensures that you have the latest libraries but they are available with great speed.
If you ever have a WordPress site that needs a little boost in the performance department then give these three plugins a try. Use Google Libraries, 1-Click Retweet/Share/Like, and WP-Super Cache can all be found on the WordPress Plugins Directory.