Optimize Performance of WordPress site

Optimize Performance of WordPress site

I have been optimizing the performance of a WordPress site for a couple of days and managed to shave off about half a second from page load times and significantly improve the performance scores.

Evaluating Performance

The first step towards optimization is to measure the performance of your site and identify the issues and bottlenecks. I used the following free online tools for this purpose:

1PageSpeed Insigths by Google
2Page Speed by varvy.com
3pingdom
4GTmetrix
5Yellow Lab Tools

It is suggested to evaluate the performance of your site using the above tools before and after each optimization to understand its impact. The impact of optimization can vary from one site to another and same techniques are not guaranteed to work across different sites. There are many factors which dictate how the site would respond to an optimization such as how dynamic the content is.

Caching

I found caching to have the biggest impact on page load times. It can be easily enabled by installing and configuring a plugin. I went with WP Super Cache plugin because out of the top three caching plugins, this is the only one which works on IIS web server. The other two, WP Fastest Cache and W3 Total Cache don’t work on IIS.

After installing and activating the plugin, the next thing is to configure it properly for getting the most out of it. I made following changes to settings of WP Super Cache:

  • Turned on ‘304 Not Modified browser caching’.
  • Changed cache timeout to about a day.
    This setting makes sense because almost all the content on the site is static in nature and new content is not posted that frequently.
  • Turned on ‘Preload Cache’ functionality.
    Rather waiting for the first user to hit a page and then generate cache for that page, this feature generates cached pages for content in advance.

Minification and Bundling

Minification removes unnecessary and redundant data from HTML, Javascript and CSS files without affecting the functionality or output. While bundling combines smaller resource files into a single file to reduce the requests browser has to make to the server.

Autoptimize is the most popular plugin to achieve this and it also works well with WP Super Cache. I turned on optimization for HTML, JavaScript and CSS code. Another option is to ‘remove Google fonts’ which can have a measurable impact on performance. I didn’t remove Google fonts as it was used by site’s theme in my case.

Content Delivery Network (CDN)

I am using Jetpack by WordPress as CDN for images.

Jetpack has servers around the world and they serve images to users from the geographically nearest server to improve performance. This also saves bandwidth on your hosting server as the request for images are served from Jetpack servers instead.

Leverage Browser Caching

We should instruct the browser to cache resources like images for a long period of time as they don’t usually change. This improves performance for repeat visits to the site.

On Apache server, this can be achieved by making changes in .htaccess file. While for IIS, I added the following highlighted line web.config file.

<configuration> 
 <system.webServer> 
  <staticContent> 
  ... 
    <clientCache cacheControlCustom="public" 
      cacheControlMode="UseMaxAge" 
      cacheControlMaxAge="31.00:00:00" /> 
  ... 
  </staticContent> 
 </system.webServer> 
</configuration>

This is going to cache static resources like images, JavaScript and CSS in the browser for 31 days. PHP / WordPress ensures that dynamically generated HTML pages are not cached for long.

No Bad Requests (Serving Woff2 font from IIS)

I found that a request for woff2 file type is returning ‘Not Found (404)’ error. The reason was that IIS didn’t recognize the file type and wasn’t serving it to the client. To fix this, I added the following to web.config file.

<xml version="1.0" encoding="UTF-8"?>
<configuration>
 <system.webServer>
  <staticContent>
  ...
   <remove fileExtension=".woff2"/>
   <mimeMap fileExtension=".woff2" mimeType="application/font-woff2"/>
  ...
  </staticContent>
 </system.webServer>
</configuration>

Results

Following are the performance scores after the optimization:

pingdom

GTmetrix

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