WordPress is by far the world’s most popular CMS. Not only does it dominate the CMS market with a 64% market share, but it also powers 39.6% of all websites. It has taken the internet by storm by democratizing the web for all. Now, anyone can build, manage, and host a successful website without needing a college degree or coding expertise.
However, while WordPress is great at managing many technical aspects, it still can’t do everything for you. Built mostly on PHP, there are often concerns regarding how performant WordPress is. And, with performance impacting everything from bounce rates to SEO rankings to conversions, it’s something that should be on your radar too.
If you don’t know it yet, images are one of the main causes of slow-loading websites. In recent years, WordPress has stepped up its efforts to try and help users with image optimization out-of-the-box.
Still, as we’ll show, it’s not a total solution, and there is still plenty you can do to deliver better experiences on your WordPress website through image optimization.
Simply put, image optimization is anything you do to make images load faster on your website pages. Almost all websites that use images can benefit from some form of image optimization, even those using WordPress.
Well, performance is a hugely significant factor when it comes to the competitiveness of your website today.
Google has also made performance an increasingly important factor when it comes to SEO rankings. In fact, performance is a direct ranking signal that carries significant weight.
Google’s Page Experience Update that went live in 2021 has been the biggest move in that direction yet. Soon, Google might even use visual indicators in SERP results to distinguish high-performing websites from the rest.
In Google’s own words, “These signals measure how users perceive the experience of interacting with a web page and contribute to our ongoing work to ensure people get the most helpful and enjoyable experiences from the web.”
According to Google, images are the largest contributor to page weight. Google has also singled out image optimization specifically as the factor with the most untapped potential for performance optimization.
This problem isn’t going away soon. According to data by the HTTP Archive, there are roughly 967.5 KB bytes of image data on desktop web pages and 866.3 KB of image data on mobile pages. This is an increase of 16.1% and 38.8%, respectively, over the last five years.
Thanks to popular e-commerce tools like Woocommerce, it’s estimated that up to 28% of all online sales happen on WordPress websites.
And don’t forget, images are both a key part of conveying information to the user and integral to the design of your website. If they take significantly longer to load than your text, for example, it will negatively impact the user experience in a variety of ways.
In summary, optimized images help your WordPress website by:
WordPress is so popular because it’s a CMS (content management system) that allows anyone to build, design, and manage a website without any coding or advanced technical experience. Advanced features can be installed with just a few clicks, thanks to plugins, and you rarely have to touch the code behind your website unless you want to make some unique modifications.
In short, using a CMS like WordPress shields you from many of the day-to-day technicalities of running a website.
As we mentioned, one of the main reasons WordPress is so popular is because it takes care of many of the technical aspects of running a website. With that in mind, many think that WordPress should also automatically take care of image optimization without them having to get involved at all.
Unfortunately, that’s not really the case.
True, WordPress does offer some built-in image optimization. Whenever you upload an image to WordPress, it currently compresses the quality to about 82% of the original (since v4.5).
In v4.4, WordPress also introduced responsive image syntax using the srcset attribute. This creates four breakpoints for each image you upload according to the default WordPress image sizes:
Here you can see an example of the actual responsive syntax code generated by WordPress:
<img loading="lazy" src="https://bleedingcosmos.com/wp-content/uploads/2021/12/33-1024x683.jpg" alt="" class="wp-image-9" width="610" height="406" srcset="https://bleedingcosmos.com/wp-content/uploads/2021/12/33-1024x683.jpg 1024w, https://bleedingcosmos.com/wp-content/uploads/2021/12/33-300x200.jpg 300w, https://bleedingcosmos.com/wp-content/uploads/2021/12/33-768x512.jpg 768w, https://bleedingcosmos.com/wp-content/uploads/2021/12/33-1536x1024.jpg 1536w" sizes="(max-width: 610px) 100vw, 610px">
Depending on the screen size of the device from which a user visits your webpage, WordPress will let the browser pick the most appropriately sized image. For example, the smallest version for mobile displays or the largest for 4K Retina screens, like those of a Mac.
While this may seem impressive, it’s only a fraction of what can be achieved using a proper image optimization solution, as we’ll show later.
Lastly, WordPress implemented HTML native default lazy loading for all images starting with version 5.5.
So, in short, WordPress offers the following image optimization capabilities baked-in:
There are other issues many have with both the implementation of image compression and responsive syntax as it’s used by WordPress. This leads to some users even purposefully deactivating WordPress’ built-in image optimization so they can fully take control of it themselves.
Here are some of the reasons why:
Another important optimization feature that WordPress does not have is auto-conversion to next-gen image file formats. Different image formats offer different performance benefits on different devices. Some formats also enable higher levels of compression while maintaining visual fidelity.
Next-gen formats like WebP, AVIF, and JPEG-2000 are considered to be the most optimal formats on compatible devices. For example, until recently, WebP would be the optimal choice on Chrome browsers, while JPEG-4000 would be optimal on Safari browsers.
However, WordPress will simply serve images in the same formats in which they were originally uploaded to all visitors.
As the undisputed king of search engines, we’ll base most of our performance metrics on guidelines established by Google.
Along with its various performance updates, Google has released a number of guidelines for developers as well as the tools to test and improve their websites according to said guidelines.
Google introduced Core Web Vitals as the primary metrics for measuring a web page’s performance and its effect on the user experience. Thus, Core Web Vitals are referred to as “user-centric performance metrics.” They are an attempt to give developers a testable and quantifiable way to measure an elusive and abstract concept such as “user experience.”
Combined with a number of other factors, Core Web Vitals constitute a major part of the overall page experience signal:
You can find a complete introduction to Core Web Vitals here. However, they currently consist of three main metrics:
Here is an illustration of how these metrics are scored:
While these are the three most important metrics to optimize, they are not the only ones. Google still measures other metrics like the FCP (First Contentful Paint), SI (Speed Index), as well as the TTFB (Time to First Byte), TBT (Total Blocking Time), and TTI (Time to Interactive).
A number of these metrics are directly affected by the images used on your web pages. For example, LCP, FCP, and SI are direct indicators of how fast the content of your web page loads and depends on the overall byte size of the page. However, it can also indirectly affect FID by keeping the main thread busy with rendering large amounts of image content or the perceived CLS by delaying the time it takes large images to load.
These metrics apply to all websites, whether they are custom-made or built using a CMS like WordPress.
When using tools like Lighthouse or PageSpeed Insights, you’ll also get scored based on other flags Google deems important. Some of them are specific to images, such as properly sizing images and serving images in next-gen formats.
If you only use built-in WordPress image optimization, you’ll get flagged for the following opportunities for improvement:
Some of the audits it will pass, however, are deferring offscreen images (lazy loading) and efficiently coding images (due to compression):
Billions of websites are all vying for prime real estate on Google SERPs, as well as the attention of an increasingly fussy internet-using public. Every inch matters when it comes to giving your website a competitive advantage.
So, how can you eliminate those remaining performance flags and deliver highly optimized images that will keep both your visitors and Google happy?
Sure, you could manually optimize images using software like PhotoShop or GIMP. However, that will take you hours for each new batch of images. Plus, you still won’t benefit from any automated adaptive optimization.
A more reasonable solution in today’s fast-paced climate is to use a tool developed specifically for maximum image optimization: an image CDN like ImageEngine.
ImageEngine is an automated, cloud-based image optimization service using device detection as well as intelligent image compression using the power of AI and machine learning. It can reduce image payloads by up to 80% while maintaining visual quality and accelerating delivery around the world thanks to its CDN with geographically dispersed PoPs.
When making a head-to-head comparison, here are the reasons why ImageEngine can deliver better performance:
So, the key differentiator is that ImageEngine can tailor optimizing images for what’s optimal for each of your visitors. ImageEngine is particularly good at serving mobile visitors thanks to WURFL device detection, which can dynamically resize images according to most devices and screen sizes in use today. As of now, this is a completely unique capability that none of its competitors offer.
It allows for far better and more fine-tuned optimization than WordPress’ across-the-board approach to compression and responsive syntax.
If you want, you could turn off WordPress responsive syntax and compression, and you would still experience a performance increase using ImageEngine. However, ImageEngine also plays nice with responsive syntax, so it’s not completely necessary unless you want to serve the highest-fidelity/low-byte-size images possible.
The process ImageEngine uses to integrate with WordPress can be broken down into a few easy steps:
Now, all ImageEngine basically does is replace your WordPress website domain in image URLs with your new ImageEngine Delivery Address. This makes it a simple, lightweight, and non-interfering plugin that works great with most other plugins and themes. It also doesn’t add unnecessary complexity or weight to your WordPress website pages.
So, now let’s get down to business by testing the performance improvement you can expect from using ImageEngine to optimize your image assets.
To do this test, we set up a basic WordPress page containing a number of high-quality images. I then used PageSpeed Insights and the Lighthouse Performance Calculator to get the performance scores before and after using ImageEngine.
Importantly, we conducted this test from a mobile-first perspective. Not only has mobile internet traffic surpassed desktop traffic globally, but Google themselves have committed to mobile-first indexing as a result.
Here is a PageSpeed score using the Lighthouse calculator for WordPress with no image optimization:
As we can see, both Core Web Vitals and other important metrics were flagged as “needs improvement.” Specifically, the LCP, FCP, and TBT. In this case, both the LCP and FCP were a high-res featured image at the top of the page.
If we go to the opportunities for improvement highlighted by PageSpeed, we see where the issues come from. We could still save as much as 4.2s of loading time by properly resizing images and a further 2.7s by serving them in next-gen formats:
So, now let’s see how much ImageEngine can improve on that.
The same test run on my WordPress website using ImageEngine got the following results:
As you can see, we now have a 100 PageSpeed score. I saved roughly 2.5s on the SI (~86%) as well as roughly 1.7s on the LCP (~60%). There was also a slight improvement in the FCP.
Not only will you enjoy a stronger page experience signal from Google, but this represents a tangible difference to visitors regarding the speed with which your website loads. That difference will lead to lower bounce rates, increased user satisfaction, and more conversions.
There was also a 53% overall reduction in the total image payload. This is impressive, considering that it’s on top of WordPress’ built-in compression and responsive syntax.
So, as someone with a WordPress website, what can you take away from this?
Well, first of all, WordPress does feature some basic image optimization. And while not perfect, it should help you offer reasonable levels of performance, even if you use a lot of image content.
However, the caveat is that WordPress applies aggressive, across-the-board compression, which will lead to a noticeable reduction in visual quality. If you use WordPress for any type of website where premium quality images are important, this is a concern — for example, as a photography portfolio, exhibition, or image marketplace like Shutterstock.
By using ImageEngine, you can reduce image payloads and accelerate delivery even further without compromising too harshly on visual quality. What’s more, ImageEngine’s adaptive image optimization technology will provide greater improvements to more of your visitors, regardless of what device(s) they use to browse the web.
Whether or not you still want to use WordPress’ built-in optimizations, ImageEngine will deliver significant improvements to your user experience, traffic metrics, and even conversions.
Plus, true to the spirit of WordPress, it’s extremely simple to set up without any advanced configuration. Just sign up for ImageEngine in 3 easy steps, install the plugin, integrate ImageEngine by copy/pasting your image domain, and you’re good to go.
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