How To Troubleshoot a Slow WordPress Install

by Ryan Cowles June 13th, 2012 

If you you've read my previous posts here on Search Engine People you have probably noticed that two things that I enjoy writing about are WordPress and Website Performance. With over 73 million sites running on WordPress it goes without saying that it is a staple in the web development community. Also, with ever increasing internet speeds on both computers and mobile devices, page load speeds are one of the most important metrics that will affect your conversions. So, we know that WordPress powers A LOT of websites, and we know that speed matters. When I recently found myself troubleshooting a painfully slow WordPress install, I realized I wasn't the only one with this problem. Let's see how we can optimize a lagging WordPress install.

The Basics

In case you missed my previous post, check out How to Optimize Your Website's Loading Time and Performance and Lazy Loading , WP Smush It, and Optimizing Your Website's Performance . If you run through those and are still experiencing problems, then it's time to get your hands dirty.

Analyze Your Plugins

p3

The WordPress community and plugin repository are incredible, and one of the reasons I love working with WordPress. However, it does also have its problems.

Since WordPress is open source, and anyone can contribute plugins to the repo, you may find some inefficient and flat out poorly coded plugins. If a plugin is poorly coded, it can put a lot of strain on your database, thus slowing WordPress down.

Lucky for us, our solution also comes in form of a plugin. Install the P3 (Plugin Performance Profiler) plugin and run a test with it. The initial results that it shows provide a lot of information, and can tell you right off the bat if a plugin is slowing your site. If so, try deactivating some of the plugins with slow loading times and see if your site is faster.

Did You Turn It Off And On Again?

on-off

If the P3 plugin didn't help you get to the bottom of things, you might have to take things into your own hands. This step can potentially save you a lot of headaches. It can also be a pain to do on a production site.

Go through your plugins one by one, and disable them. Then view the site and see if the performance issues are still present. If you notice your site is a lot snappier and responsive, it's safe to say a plugin was causing the problems.

Try reactivating them one by one, viewing the site each time to see which is the cause. If you deactivate all your plugins and the site is still slow, try reverting to the default Twenty Twelve theme for WordPress. If your site is faster, then it's a big possibility that your theme was causing the problems.

Optimize Your Database

optimize

As your WordPress site ages, and you add new features and remove old, your MySQL Database can get filled with unneeded clutter. All databases need to be optimized, and if you haven't set up a cron job to do so, then you will need to do it manually.

Login to your database via phpMyAdmin, and navigate to your WordPress database. At the bottom you will see a link that says "Check tables having overhead." True to its name, this will select all the tables that have overhead. Now all you have to do is choose "Optimize Tables" in the "With Selected" drop down menu. This process is similar to defragging a harddrive, and it should be done regularly.

While you're in there, you may also want to check out your wp_options table. This table holds your default WordPress settings. Some plugins also use it to store settings. If you haven't checked it out before, I suggest that you read my article, How to Optimize Your wp_options Table in WordPress.

Conclusion

So, you've analyzed your plugins. You've optimized your database. You've optimized the front end of your site, using Lazy Loading, WP Smush It, and general best practices for optimization. You should now have a happy WordPress install, that loads quickly and most importantly, makes your visitors happy.

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Ryan Cowles

Ryan Cowles is a WordPress / Front End Developer living in Los Angeles, California. Along with a passion for building creative websites, he also enjoys photography, design, travel and the great outdoors. You can view his personal website by visiting http://ryanscowles.com. To see what he has been up to lately, check out his blog at Metacom Creative.

Ryan S. Cowles

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5 Responses to “How To Troubleshoot a Slow WordPress Install”

  1. Leo says:

    The 'Tried turning it off and on again' made me chuckle, reminded me of the IT Crowd :D

    Very useful post and this information is hard to come by. I am (or was) quite convinced that one of the WP websites I'm running for a client has experienced a dip in speed and load times because of the webhost service we went for, but I'll now definitely give that P3 plugin a go before getting in touch with them. Thanks!

    • Ryan Cowles says:

      Hi Leo!

      I'm glad you were able to find this post useful. Another thing you should check is your Post Revisions. There is a plugin called WP-Optimize that can clear out your post revisions for you, and also help you optimize the database. Overtime, post revisions can really build up. If you're sure that you won't be needing them in the future, I highly recommend cleaning them up. Thanks for the reply!

    • Leo says:

      Will get WP-Optimize and check. Thanks for the tip!

  2. The "tried the on and off button" part is funny but unfortunately with WordPress, but I must say I'm missing a piece of advice here probably because I made this mistake many times in the past:

    Updating WordPress to the latest version is NOT always the best idea. Sometimes you really need that one conversion optimization plugin or metrics plugin or whatever that breaks because the latest WP version isn't supported. Result: slow load speed OR a site that's not loading at all + a plugin you really needed doesn't work anymore.

    Also think twice before updating plugins: the latest and greatest version sometimes may not support your version of WP (anymore) and thus the same thing happens: breaking the site… or the plugin.

    Sorry for my rant about plugins there, but they do influence load speed AND other things.

    Regards,

    Dennis Miedema

    • Ryan Cowles says:

      Hi Dennis,

      Thanks for your reply! While sometimes the latest version of WordPress may cause older plugins to fail, I still recommend updating, especially if there are security updates in the latest release. As for plugins, I usually wait to see what the response from the rest of the community is. By logging into your Dashboard and checking the updates page, you can even see how many people say the latest version of the plugin works (or doesn't work) with your version of WordPress. However, even if you don't want to upgrade right away, I highly recommend checking the Change log to make sure the update doesn't contain any security patches.
      Thanks again for your input!
      Ryan