The Image CDN feature delivers images from Jetpack's Content Delivery Network (CDN). The CDN Automatically resizes your images to an appropriate size, converts them to modern, efficient formats like WebP, and serves them from a worldwide network of servers. When I have uploaded later edits of images, I have had issues with the CDN serving the old versions of images instead of the updated version. I did not enable the Image CDN feature.
However, I was only partially happy with the results. When I ran a test using PageSpeed Insights, I got a pretty shitty score with a message that the website had failed the Core Web Vitals Assessment. I wanted to do better. The cool thing about PageSpeed Insights is that it will diagnose performance issues and suggest recommendations for improvement. PageSpeed Insights recommended using a more optimised theme, an optimisation plugin, or upgrading the server.
I’m using an IndieWeb version of the Twenty Sixteen theme. It has an additional markup for microformat2, which could be causing some performance issues. However, removing that code is not an option since I need microformat2 support to use the IndieWeb plugins. I’m using a fairly robust virtual private server from Digital Ocean. I don’t see any issues in the Digital Ocean dashboard to indicate that server performance is an issue.
The other recommendation from PageSpeed Insights was to use the Performance Lab plugin to convert uploaded JPEG images into WebP automatically. The Image CDN feature of JetPack Boost does this, but as I mentioned before, I have had issues with the CDN serving the old versions of images even after new ones are uploaded.
That left me with one viable option: an optimisation plugin. The WordPress HealthCheck feature kept complaining that I had no object caching service installed. It recommended Redis. After reading How to Setup Redis Caching for WordPress with Ubuntu 20.04 and Nginx and How to Install Redis on Ubuntu 20.04 / 18.04, I installed and configured a Redis server. I also installed and configured the Redis Object Cache plugin by Till Krüss.
As a starting point, I used the following settings from the INSTALL.md on the Redis GitHub. ** Please make sure to change the cache keys to something unique**. I used the wordpress.org salt generator to create a unique key for my installation. By default, the object cache will connect to Redis Server over TCP at 127.0.0.1:6379. For security reasons, I explicitly defined the host and port settings.
//Adjust Redis host and port if necessary ?define( 'WP_REDIS_HOST', '127.0.0.1' );?define( 'WP_REDIS_PORT', 6379 );??// Set a cache key salt and enable a persistent cache with the Redis object cache plugin?define('WP_CACHE_KEY_SALT', ’example.com');?define('WP_CACHE', true); ??// Reasonable connection and read+write timeouts?define( 'WP_REDIS_TIMEOUT', 1 ); ?define( 'WP_REDIS_READ_TIMEOUT', 1 );?
There are other Redis settings that I want to learn more about before enabling them.
|WP_REDIS_PASSWORD||The password of the Redis server. Supports Redis ACLs arrays: ['user', 'password']|
Since I have set the Redis server to only listen on
WP_REDIS_SCHEME isn’t critical. However, this setting would add another layer of security.
Results and Up Next
JetPack Boost said my website performance had fallen after enabling Redis. There was a caveat message from JetPack Boost Most of the time, JetPack Boost will increase website speed, but there may be cases where the score does not increase. The JetPack Boost documentation on improving the Site Speed Score recommended using Google’s PageSpeed Insights tool. I found that suggestion humorous. I considered if there was a conflict between JetPack Boost and Redis and how JetPack Boost reports performance. I decided to rely on the results from PageSpeed Insights.
Disabling the Optimize Critical CSS Loading of JetPack boost improved the Desktop Score but worsened the Mobile Sore significantly. I’ll keep experimenting and reading and learning about Redis. I want to ensure I have optimised my website as much as possible. Seeing the word, Failed on the PageSpeed Insights test agitates me.
Jim Grey appears to be using the Yoast SEO caching plugin. I ran one of his posts through PageSpeed Insights, and his website got a Core Web Vitals Assessment: Passed. I’ll try using a caching plugin with Redis and see what happens.