While not the only factors, there are three critical areas to be addressed when it comes to all things site speed. These are sure to speed up your site.
I’ve outlined each below.
1. Image/Asset Optimization
We know that large, uncompressed images and videos will slow down your site to a crawl.
So it is of the utmost importance to utilize image compression and lazy loading of off-screen images, to ensure your site performs its best in both site speed testing and real world application.
Tools To Use
The Smush Pro plugin (https://premium.wpmudev.org/project/wp-smush-pro), from WPMU Dev, is a user-friendly optimization tool for lazy loading, and lossless compression of not only your existing images, but also any assets uploaded in the future.
We have two attribute options widely accepted by all browsers: defer or async.
When we defer parse internal js files, we tell the browser to load the page, before running the script. The async attribute is similar, but is used for external assets.
We are essentially telling the browser that it can download the script while the page is loading, and to pause the site load and run the script only after downloading of the script has been completed.
Without adding async to the <script> tag, your site with pause to fetch, and then run the script, prior to parsing the html.
Tools To Use
It is important to keep in mind, when utilizing this plugin, that most WordPress builders will have to be added to the exclude list, so that the visual output integrity is maintained.
3. Leveraging Browser Cache
Serving your assets and files from a content delivery network is, hands down, the best option for passing this criteria in site speed tests, and providing your end users with the best possible user experience.
There are a number of CDN options to choose from, but whichever you utilize will go a long way in speeding up your website.
In addition to adding a CDN to your tool box, cache plugins can help in serving static assets to your visitors.
Tools To Use
A favorite here is WP Super Cache (https://wordpress.org/plugins/wp-super-cache).
With this plugin, “99% of your visitors will be served static html files. One cached file can be served thousands of times. Other visitors will be served custom cached files tailored to their visit. If they are logged in, or have left comments, those details will be displayed and cached for them.”
These aren’t the end all be all of site speed optimization techniques, but they are sure to get you on your way to having a lightning fast website.