What are the best site performance plugins for WordPress?

The huge range of plugins available within WordPress is one of its key strengths. But with the WordPress Plugin Directory now featuring above 55,000, how on earth can a developer see the wood for the trees and make sound choices for constructing a secure and maintainable site?

At Sereno, we have evolved a set of plugins that we deploy on all our new WordPress sites. This doesn't mean that its the only sensible set to opt for, but whichever plugins you go for, make sure they work well together and there isn't too much overlap of functionality between them. They should be complementary to one another.

Here is our experience of going through this plugin picking process to make WordPress as fast as possible. While these plugins may offer paid-for extra features, all of them can make your site faster for free:

Autoptimize

https://en-gb.wordpress.org/plugins/autoptimize/

A lot of the bits and bytes that are downloaded when you visit a web page are not visible content - they are scipts and styling files. Rather than leaving these in dozens of separate files slowing up your page, Autoptimize will automatically smush these into just one or two files.

It offers plenty of options, but the default will help you make your site quicker out of the box.

EWWW Image Optimizer

https://en-gb.wordpress.org/plugins/ewww-image-optimizer/

This plugin will compress your images, making them smaller for your site visitors to download and also gobbling up less of your precious disk space. There are more advanced options around lazy loading and using the format webp. These take a bit more configuration, but you can get started by just switching on the plugin and taking advantage of its image compression and scaling capabilities out of the box.

Imsanity

https://en-gb.wordpress.org/plugins/imsanity/

This solves the problem of your clients uploading huge images. Imsanity will automatically scale them, on upload, to your chosen maximum dimensions.

Imsanity also provides a bulk-resize feature to resize previously uploaded images and free up disk space. It also allows you to resize individual images from the Media Library’s List View. This is really useful if you have a mature site over-using disk space, allowing you to conduct a review and make some savings.

Query Monitor

https://en-gb.wordpress.org/plugins/query-monitor/

This isn't specifically a plugin which offers performance improvements automatically. However, if you know you have a performance problem, Query Monitor can offer technical insights into where the bottlenecks or errors are. It's unwise to keep this running on a production server, but super useful for testing environments. It's one for developers.

Regenerate Thumbnails

https://en-gb.wordpress.org/plugins/regenerate-thumbnails/

WordPress will automatically create thumbnails for your images when you upload them. But what happens when you add a new thumbnail size during a redesign, or make a change to the dimensions of an existing thumbnail? Or perhaps you’ve switched theme and the new one uses different sized thumbnails?

Regenerate Thumbnails can also automatically delete any old obsolete thumbnails for you, if you are no longer using a certain thumbnail size. This keeps disk usage to a minimum.

WP Super Cache

https://en-gb.wordpress.org/plugins/wp-super-cache/

WP Super Cache generates static html files from your dynamic WordPress pages and posts. Your web server will serve that file instead of processing the expensive WordPress PHP scripts with every visit.

The static html files will be served to the vast majority of your users:

• Users who are not logged in.
• Users who have not left a comment on your blog.
• Or users who have not viewed a password protected post.

In other words, 99% of your visitors will be served static html files. One cached file can be served thousands of times. The advantage here is the speed the visitor encounters.

The combination of these plugins, and spending some time with configuration and testing, can really speed things up for your users. In turn, this can help with your site's SEO. Search engines like Google will use your site pages' load times as one factor when prioritising (or not!) your website's search results.

I hope you find this review of WordPress site performance plugins helps you build quicker sites with super fast page loads!