Do Plugins Affect WordPress Performance? Real Test Data

“Too many plugins will slow your site down”. If you’ve spent any time learning about WordPress, you’ve probably seen this statement. Is it true, though? And just how much do plugins affect WordPress performance?

In general, there’s no hard cap on the number of plugins that you can run on your WordPress site. While that doesn’t mean you should go crazy installing every plugin in the WordPress.org repository, there’s no reason to believe that the simple act of installing “more” WordPress plugins by itself is bad for your site’s performance.

To help prove that point, we’re going to perform real tests on how some common categories of WordPress plugins affect load times. At the end, we’ll compare loading times, and find out how much plugins affect WordPress performance.

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How we conducted our performance tests

An example of multiple plugins active on a site.

Most WordPress websites use multiple plugins simultaneously.

Testing a site’s performance is easy enough. You can use tools such as Pingdom to run speed tests in seconds, although it’s best to repeat them a few times and find an average. For our test, we used a simple website with WordPress’ theme unit test data installed on it, to simulate a site with a decent amount of content:

This website is hosted on Flywheel, which guarantees top performance.

To start off, we tested how long the site itself took to load using Pingdom Tools. That gave us a baseline for our later comparisons. Then we installed plugins from five popular categories and re-tested our loading times to see what impact the plugins had. After each test, we restored our website to its initial state to wipe the slate clean.

How five types of plugins affect WordPress performance

As we mentioned, we first tested our homepage’s base loading speed with Pingdom Tools. We used the San Jose, California server, and repeated the test three times to get an average. After all, results often vary quite a bit between instances.

According to Pingdom Tools, our initial test site took 0.93 seconds to load. Let’s find out how much plugins affect WordPress performance!

(Charts by Visualizer Lite.)

1. Security Plugins

For this test, we’re going to set up the Wordfence plugin on our website. It’s one of the most popular and comprehensive security plugins on the market, thanks to its all-in-one approach to protecting your site:

Its wealth of features should make the plugin more resource-heavy than most. In fact, after installing it, we went from a loading time of 0.93 seconds to an average of 1.13 seconds. As with all subsequent plugins, we ran the test on this one three times.

(The no-plugin benchmark time in green.)

Here are the results from one of those instances:

From a big picture perspective, .20 seconds by itself is a fairly small increase. And in this instance, the plugin’s features may justify it (depending on your needs).

2. Backup Plugins

Backup plugins are critical for most WordPress sites. Unless your web host offers you automatic backups, you need a tool to help you back up your WordPress site. Personally, we’re big fans of UpdraftPlus:

Unlike security plugins, this type of tool doesn’t do a lot of work behind the scenes until it’s time for a scheduled backup or you need to restore your website. That means it shouldn’t have any noticeable impact on your front-end load times.

Our tests seem to confirm that assumption:

Our loading times, in this case, averaged 0.94 seconds, which is virtually the same as our initial test site. This is a good example of how plugins by themselves don’t necessarily add to your load times.

3. Contact form plugins

Contact forms are one of most popular website features around. Regardless of what type of site you’re running, chances are you decided to include a contact form somewhere. Since Contact Form 7 is the most popular option for WordPress, it made sense to test Contact Form 7 to see how it impacts our site’s performance:

As far as our tests can determine, this particular plugin had little to no effect on our site’s speed. This makes sense when you consider that a well-coded contact form plugin should only affect the page where it displays:

After installing it, our average loading time was just 0.96 seconds, which is again virtually the same as our initial test site.

4. Search Engine Optimization (SEO) plugins

SEO is one of the most important strategies you can use to get more eyes on your website. That’s one of the reasons plugins such as Yoast SEO are so popular:

Yoast SEO is a comprehensive tool that runs on virtually every single front-end page on your website. Because it’s so ubiquitous, it makes sense that Yoast SEO has a slight affect on page load times:

In this case, our average loading time went up to 1.03 seconds. This is to be expected, considering the plugin’s wealth of functionality, but it’s still a reasonably significant impact.

5. E-commerce plugins

Finally, e-commerce plugins are one of the most interesting categories we decided to test. After all, they tend to add a staggering amount of functionality to WordPress, and WooCommerce is no exception:

With a plugin that does this much, it’s only logical to expect a small hit to performance. Our tests confirmed that theory:

In this case, we walked away with a loading time average of 1.22 seconds. That’s by far the biggest hit to performance we’ve seen, but it’s to be expected from this category of plugin.

Do WordPress plugins affect your loading times?

The short answer to this question is that plugins definitely do have the capability to affect your loading times. But there’s no rule for “how much”. Some plugins, like backup and contact form plugins, should have no noticeable effect on your site. While others, like e-commerce plugins, are likely to add at least some time to your page load times:

Do plugins affect WordPress performance?
	Base loading time (in seconds)	Loading time after install (in seconds)	Change in %
Security plugins	0.93 s	1.13 s	21.50%
Backup plugins	0.93 s	0.94 s	1.07%
Contact form plugins	0.93 s	0.96 s	3.22%
SEO plugins	0.93 s	1.03 s	10.75%
E-commerce plugins	0.93 s	1.22 s	31.10%

Overall, while it’s true that some plugins affect WordPress performance, you should be more than fine if your site is well optimized and you select quality plugins. Your choice of web host and plan will also be a determining factor.

That is, there’s no hard number for how many plugins you can have. As long as you pay attention to your site’s performance, feel free to install as many plugins as you want. You can find plenty of respected WordPress developers (like Samuel Wood and Pippin Williamson) to back up this point:

Paraphrased from @Otto42 today at #wckc : “no, you can’t have too many plugins. It is quality and scale that matters.” – thank you!
— Pippin Williamson (@pippinsplugins) June 4, 2012

Just to be thorough, we also ran a test with all five plugins active simultaneously, and our loading times came out to an average of 1.20 seconds. This indicates that adding more plugins doesn’t necessarily translate to a linear decrease in site performance.

Conclusion

People often talk about how much plugins affect WordPress performance. However, it isn’t always easy to find hard data to back up those assertions. That’s why we decided to test some highly popular plugins on our own, to gauge their impact on a basic WordPress site.

During our tests, we found that most categories of plugins don’t seem to have a noticeable impact on your site’s performance. That is, of course, if you’re using a quality web host. If your site always feels sluggish, chances are it has more to do with poor optimization than with your choice of plugins.

Have you been having any problems with too many plugins affecting your WordPress performance? Share your stories with us in the comments section below!

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Do Plugins Affect WordPress Performance? Real Test Data

How we conducted our performance tests