Slow Wordpress Site? A Primer on Speeding It Up

April 23rd, 2017

Nobody likes a slow Wordpress site. Slow loading times not only cost visitors/sales, but can also hurt a site’s Google ranking. If your website is mission-critical and you’ve noticed it takes a while to load, it would be well worth spending some time sorting the issue out, but where to begin?

The importance of benchmarking

One of the best ways to quantifiably measure a site’s speed is to use an independent website performance tool. There are lots of these available and they generally work by ranking your site based on various site performance factors. Perhaps the most well known is Google PageSpeed, but others include GTmetrix, Pingdom, WebPagetest and Varvy.

These tools are extremely useful as they not only allow you to independently confirm that there's an issue in the first place, but also enable you to track your progress as you tweak different aspects of your site. However, these tools are only useful if you understand what they’re testing and, therefore, what they can tell you about your site.

What Google PageSpeed doesn’t tell you

One of the most common misconceptions is that Google PageSpeed tells you how fast your site loads. It doesn’t! PageSpeed doesn’t actually measure how fast your site loads (it would likely tell you how many seconds your site took to load if it did), it simply ranks factors that could be causing your site to load slowly.

This is a great example of why it’s important to understand what each of the tools can tell you about your site’s performance. If you want to measure the actual load time of a site, you would need to use a tool such as GTmetrix or Pingdom, but even then the figures vary and might be telling you different things.

It’s worth noting that testing the actual load time of site is tricky due to the number of variables that can affect the figures given. Where is the user located? What type of device are they using? What’s their connection like?

The best approach is to see these figures as a rough indicator and try to reduce them as much as possible. Probably the most useful tool for this is Pingdom’s site, which can tell you the percentage of tested sites that the URL loads faster than.

Given all of these factors, it’s a good idea to use a couple of tools that complement each other and can give you an overall picture of how your site’s doing.

Quick tip #1: Make sure you test the correct URL to get the most accurate results. For instance, if you tested when the website address is actually, this could give a slightly different result. The same applies to http/https, too.

What the tools tell you

Less confusingly, the tools highlight trouble areas with some more tangible aspects of your site. These factors include, but certainly aren’t limited to:

This is useful to know because you can then go about the task of tackling each one. If you perform another test after each round of updates, you will start to see the areas that improve site performance the most.

Quick tip #2: Aside from making sure the tested URL is accurate, try changing the location of the test, too. The server location should be close to where most of your users are, so if your site is hosted in the US and your users are in the UK, this could also be a factor.


There are many factors that lead to slow Wordpress sites, but two of the main culprits are browser caching and image optimisation...or a lack thereof.

Uncompressed, full-resolution images are one of the quickest ways to bring a website to a complete standstill. Therefore, scale down images to the size that you need them before uploading a use a tool such as ShortPixel* to compress them further by using lossy or lossless optimisation.

Browser caching is another method of significantly improving the performance of a website, too. There are lots of excellent free Wordpress plugins that can help to achieve this, though the most popular are undoubtedly W3 Total Cache and WP Super Cache. It’s possible to achieve significantly improve the performance of slow Wordpress sites using these plugins, so they are highly recommended.

A relatively new player on the Wordpress caching scene is WP Rocket*. This is a premium plugin ($39) that offers a quick method of lazy loading images and iframes across a site, which is a great benefit. I found this plugin to offer consistent improvement across a range of client sites that I performed benchmark comparison tests on, so I now install this caching plugin as standard on new WordPress site developments.

Server environment

If your site is well optimised but page load times are still slow, it might be time to look into whether this is a hosting issue. This can be indicated in a number of ways, possibly a slow TTFB (time to first byte), slow performance despite a light web page or long wait times in performance waterfalls.

Shared hosting is great way to get a site online cheaply but some hosts will cram thousands of sites on to a single server. This isn’t necessarily an issue if they are all low traffic sites, but if some of these suddenly experience high traffic volumes it can put pressure on all of the other sites, causing slow response times across the board.

To tackle this, make sure you use a reputable host. Kinsta* are an excellent Wordpress host and I can highly recommend Guru* for UK users, too. Both of these offer great shared plans, though for more performance you may want to upgrade to a VPS or Dedicated Server if funds allow.

Goal setting

Ultimately, you have to be realistic about what will be achievable and exactly what the goal is for your site. Wordpress site performance can often be dramatically improved but the server, theme and plugins can place limitations on what’s achievable.

It’s also important not to chase specific numbers on performance tools, though of course these should be improved as much as possible. In fact, it’s perfectly possible to have a site that doesn’t have a flawless PageSpeed score that still loads very quickly.

For example, Google PageSpeed will often recommend ‘Eliminate render-blocking JavaScript and CSS in above-the-fold content’. This is certainly a warning to take note of but it’s also bearing in mind that this can be an almost impossible warning to remove.

The best tool for the job is almost certainly Autoptimize, which is a fantastic plugin, but to properly mitigate against this it needs to be combined with Even if this is fully implemented, it may not completely remove the PageSpeed warning and will require much upkeep if the site is under development.

If you weigh all of this up, the time/cost investment may be too much for what could be a small performance improvement, but it shouldn’t necessarily be completely ruled out.

Help! I have a slow WordPress site!

You should now have a bit more of an understanding of what is causing your site to be slow, what you can do about it and, perhaps most importantly, how to measure it all. If you have a slow Wordpress site and would like some help speeding it up, please get in touch.