Testing the speed of comment systems for blogs

For blogs and many other types of sites, getting an interaction going with readers is essential. But it would seem that many believe that installing a third-party comment system on a website, something like Disqus, IntenseDebate, or LiveFyre, drags down the site’s speed considerably.

Instead of spurring on debate, discussion, and interaction, a slower site could discourage users to take part, and users could instead end up leaving the site. But is it really the case that adding these comment systems slow down sites?

We put five comment systems to the test and found out that there’s less difference in speed than you might think.

Comments are important

First, let’s establish that comments are important for many websites, not just blogs. We think comments are a critical component of our blogs at Pingdom, and we have posted before asking for feedback on which third-party comment system we should go with, if any.  As you can see, we still use WordPress’ built-in comment system, but we are right now looking at alternatives.

For example, in December we noted that Disqus has a commanding lead in the Technorati Top 100 blogs, where it had a 22% market share. In the comments to that article we got many good opinions and suggestions as to what we should do.

But if installing a third-party comment system will slow a site down, then it’s something that many webmasters will not want to do. Since users like speedy sites – customers are often won or lost in mere seconds – webmasters obviously take this very seriously.

Number of files loaded (requests)

So we put five of the more common comment systems to the test:

  1. WordPress’ built-in comment system
  2. Disqus
  3. Facebook
  4. IntenseDebate
  5. LiveFyre.

You can read more about how we did the testing at the end of the article.

First, we looked at how many requests were made when using the different comment systems. With our testing site, we saw 6 files being loaded in with just plain WordPress, without any third-party comment system. Disqus and LiveFyre each loaded 9 files, IntenseDebate 11 files, and Facebook 14 files.

Page size

You would perhaps expect that this difference in number of files that are being downloaded mean a big difference in the total size being requested when the site is loaded. However, there is not much difference between plain WordPress and three of the third-party systems: Disqus, IntenseDebate, and LiveFyre. For example, the difference between WordPress and Disqus, was only about 4 kB.

The only comment system that really stuck out in terms of page size was Facebook, which required almost 47 kb extra to be loaded compared to plain WordPress. Although this, in and of itself, may not seem like much, it’s very likely a website will also have other plugins and additions installed, each requiring something additional to be loaded, so the page size can then quickly increase.

Website performance

But of course page size and number of files don’t necessarily accurately reflect how fast or slow a website is as perceived by a user. Here’s how the sites fared when we looked at the time it took to load them:

What this showed us is that again there is not that much difference between the five different comment systems, with a few exceptions. WordPress is, in each instance, the fastest one to load, but it’s only when testing from Amsterdam it crushes the others.

When we then finally combined the results from each location, and looked at an average loading speed for each of the comment systems, this is what we got:

Again, as you can clearly see, there was not that much of a difference between using WordPress’ built-in comment system and any of the other four, third-party systems. We would even go so far as to guess that there was less of a difference than you would have thought before reading this.

Not a big drag on site performance

The conclusion must be that there is not such a big difference in website performance between running just plain WordPress and having one of these third-party comment systems installed. That is, with the possible exception of Facebook.

Of course this is just a very limited test, which doesn’t necessarily reflect real-life cases, where multiple users access a site running multiple plugins, and other modifications. Where servers are located also play a role, as does where content is located (on a CDN, for example).

That said, we think it indicates that installing a third-party comment system does not necessarily drag down a site’s performance. At least there is not a big difference in performance in our tests.

Could there be other things adding to the issue of users perceiving sites with these add-ons installed as slow? Let us know what you think. You can also test your website speed using Pingdom’s site speed tool.

Take our poll

We created a simple, one-question poll, trying to gauge what our readers would prefer to see implemented here on the Royal Pingdom site.

Click here to take the poll!

How we tested: We tested on a WordPress site, which was hosted in Sweden. It had the latest WordPress, 3.3.1, and all plugins were up to date. However, we disabled all plugins other than the ones needed for each comment system to work. We also used the default WordPress theme with no modifications, just so we could get a test that was as fair as possible. For each comment system we used the corresponding official WordPress plugin, with the exception of Facebook, for which we used the Simple Facebook Comments plugin. We tested ten times for each comment plugin from all three testing sites that our Tools uses (tools.pingdom.com/fpt): Amsterdam, The Netherlands, Dallas, Texas, USA, and New York City, New York, USA. From the ten tests we then took the average for requests, page size, and performance.

Speech bubble image via Shutterstock.


  1. I think it’s important to point out, however, that features matter. Disqus is hands down the best comment system I’ve ever come across; the single sign-on + very controlled notifications = perfection. I also think Disqus could be considered faster since it’s asynchronous, loaded after the page loads. WordPress comments are part of the page’s HTML, and slow down the initial and most crucial load of all (although likely not by much).

    9 times out of 10, if I don’t see Disqus, I won’t comment. Seeing Facebook in particular is a huge turn-off.

    1. Michael, have you even tried the newer system called Livefyre? Lots more socially and the ability to merge and post is much faster and cleaner than Disqus.
      BTW, do you really use Yahoo to log into anything anymore?

  2. Comments are vital to your website,right? You are putting lot of trust in a third party who has no obligation to provide the service. If it’s offline you have no comments. If they Lose their data all your comments are gone. Yes they do have a good offering and appeal to end users. Personally I’d rather be in control of my own destiny.

  3. Rob, some if not all of these third-party comment systems save all comments also into the native WordPress database. So if you later remove the plugin, WordPress can still serve up the comments.

  4. Michael, we agree completely that features matter. And that’s the main reason why we are looking at installing something that offers more functionality over and above what WordPress does.

  5. WordPress’ comments actually add more of a performance hit. You have the data retrieval and processing of the comments. Another issue is with the cookies WP uses to store your username, email and website. Instead of being handled through javascript, this is handled inside of PHP. That means any page caching mechanisms no longer work once someone posts a comment. That can be a serious impact, especially on sites with a lot of comments.

    The 3rd party systems are generally a lot better since it reduces the load to your server. Incidentally I’m in the middle of writing an external commenting system for a large Drupal site that sees a lot of comments. It’s really been an interesting project and so far the performance improvements have far exceeded my expectations.

  6. Food for thought: What are the 3rd party vendors doing with the audience data they collect on your site’s back? Using FB as an example, when you use their tags they learn more about your audience than you do and can leverage that in a multitude of ways (advertising being the most common). With wordpress directly on your server, there’s no middleman learning about our site’s audience and compiling the information into a datawarehouse.

  7. The problem as far as I am concerned it not the speed, but the fact that some comment systems just don’t play nicely with all browsers

    Disqus flat refuses to work with Opera, and the people who make the posterous blog platform have told me Opera support is a “coming soon” feature.

    I know, I could use another browser but using Opera reminds me constantly to make sure any website I design works on every browser, and every platform.

    I’m afraid I could name check so many sites that still, these days, only support IE properly.

  8. what about google’s blogger comment system? ideally it was an older one and harder to customize but the recent changes of threaded comment system also good over there.

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  10. I want a system that allows me to have multiple comment threads on the same page (one after each article). I like Disqus but it doesn’t support this. Maybe livefyre does?

  11. Disqus appears to be the most popular when I am visiting websites but I really dislike it. Especially on mobile. It seems to take forever to load and stays in a “loading comments” phase forever in that I have to refresh the page itself for it to finally work.

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