Yoast SEO is a popular SEO enablement plugin for WordPress. It helps you avoid common mistakes when it comes to SEO on your blog and also handles things like social media “og:meta” tags. If your blog has a public audience, then it stands a good chance that you are using Yoast.
As with the previous article in this series, we’ll focus on what performance implications are of using Yoast and how you can make it faster.
What was tested?
For this test we used the lowest-tier (1vCPU, 1GB RAM, $5) DigitalOcean droplet out of their SFO2 datacenter. Our server setup was as follows:
- Ubuntu 19.04 with all updates installed.
- Nginx 1.16.1
- PHP-FPM 7.3
- MariaDB 10.3
The theme that was used was TwentyTwenty with no modifications and the content tested was 3 “What’s new with Kernl?” posts from earlier this year. We selected a small number due to the effort of filling out all of the SEO data in Yoast.
The WordPress setup was bare-bones. There were no plugins installed except for when we were running the Yoast test.
As with our previous post in this series, the load for this test was generated out of DigitalOcean’s NYC3 datacenter.
Test Methodology
For testing Yoast we only ran two tests:
The tests were with 200 concurrent users over the course of 1 hour.
Max Requests per Second
One method for determining website performance is what is the maximum number of requests that in can field in a given second. For our purposes this is a pretty good indicator of the performance hit you take for installing plugins.
As you can see from the image above you lose about 25% of your maximum capacity from installing Yoast SEO. With no plugins installed we were able to hit 43 req/s, while with Yoast installed that number went down to 30 req/s.
It’s worth noting here that 30 req/s is 2.5 million requests a day.
First Error Occurrence
The next chart shows when we first started to see errors in our two tests.
Without the plugin installed WordPress was able to hit 38 req/s before seeing errors. Once we enabled Yoast that number went down to 28 req/s. Once again, this is consistent with the performance penalty we saw with the maximum requests per second of about 25%.
Average Response Time
The average response time with and without Yoast SEO tells a similar story to the requests per second measures we have done.
The chart above shows us that without any plugins installed, the average response time under load is around 3000ms. With the Yoast plugin installed the response time goes up to about 4300ms. We’re looking at a roughly 25% change in response time.
99th Percentile Response Time
The 99th percentile chart can be read as “99% of all requests finished in under this time”.
The chart above tells us that without any plugins installed 99% of our requests finished in under ~3600ms. With Yoast SEO installed 99% of our requests finished in ~4900ms. Once again, a roughly 25% penalty for having Yoast installed.
Yoast SEO Performance Conclusions
Yoast is a really good SEO plugin. If SEO matters to you it’s definitely a plugin you should have installed. However you should use caching if you do use it. This goes for WordPress in general, but every plugin you add to WordPress has a performance cost associated with it. If you run a site where caching is difficult you’ll have to carefully weigh the performance cost versus benefit of installing Yoast SEO.