Welcome to the end of 2019! I hope that everyone has had as good a year as Kernl. Let’s dive in to the final update of 2019 to see what’s new.
Features, Bug Fixes, & Misc.
Improved License Management Search – License management now includes improved search functionality. The previous search functionality was flaky (at best) and not very discoverable. Search is now a first-class citizen, includes free-text search, and should greatly improve the overall usability of Kernl’s WordPress license management.
Load Testing Unit & Integration Tests – When we created the WordPress load testing service it was an experiment. Now that we have proved the viability of the service it’s time to work on stability and overall platform longevity. This month’s focus was on the authorization framework that our load testing service uses.
JS Bundle Size Reduction – Over the past year Kernl’s JS bundle size for our web app grew to over 2MB. We spent some time this month figuring out why and making changes to reduce it. In the end we were able to reduce the bundle size by over 50% down to 1.1MB.
Bug: Inconsistent Webhook & Deploy Key Behavior – After a few customer reported incidents with the automatic webhook and deploy key behavior, we discovered that Kernl wasn’t deleting local references to remote keys and hooks. If you have some issues with deploy keys or webhooks please contact us and we can help resolve the data inconsistency issues that this caused.
Node.js Upgrade to 12.14.0 – This month we upgrade all of our servers to use the latest LTS version of Node. This is includes stability and performance improvements.
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.
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.
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.
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.
If you are just starting with Cloudways it can be tough to figure out where your money is best spent! The prices are different for each platform and how they are sized isn’t them same either. This review gathers data using Kernl’s WordPress Load Testing tool and then massages that data into someone easy to digest.
Google Cloud – A “small” instance out of their Northern Virginia data center. $39.36 / month.
Amazon Web Services – A “small” instance out of their Northern Virginia data center. $36.51 / month.
Vultr – “2GB” plan out of their New Jersey data center. $23 / month
Linode – “2GB” plan from their New Jersey data center. $24 / month
Digital Ocean – “2GB” plan from one of the New York City data centers. $22 / month.
And we had the following load testing setup:
Content was an export of this blog
1000 concurrent users
30 minute duration
3 users per second ramp up
Load generating machines were in the San Francisco #2 Digital Ocean data center.
Overall Cloudways Performance and Value
Each provider performed extremely well in our tests. No errors were reported and they all reached over 700 requests / s sustained traffic. However not all hosts are created equal.
Costs / Month (cents)
$ / 1000 req (cents)
Given that each load test was exactly the same, you can see that some hosts performed better than others.
AWS and GCP are a bit more costly than Linode, Vultr, and Digital Ocean and they also performed worse than the lower cost providers.
Cloudways Provider Response Times
While cost per requests is a good metric we also care about the quality of those requests. Quality can be measured in a number of ways, but response time is often a “good enough” measure of how well a particular host performs. For the providers that you can get through Cloudways, the variance in request quality is extremely interesting.
The chart below shows the 99th percentile response time performance for each provider. It means that 99% of all requests during the load test finished at or below this time.
You can see that lower cost providers once again out-perform the higher cost AWS and GCP in pretty significant ways. The really interesting result here is that Vultr responded to 99% of requests in 240ms or less! Way to go Vultr!
If you aren’t sure which provider is the best value on Cloudways, from a raw cents per requests perspective you can’t go wrong with Linode, Vultr, and Digital Ocean. It’s the same story when you consider the quality (re: response time) of service: Vultr, Linode, and Digital Ocean are the clear winners here.