How to Fix Excessive DOM Size in WordPress (11 Expert Tips)

As a WordPress expert with over 15 years of experience, I’ve seen firsthand how a bloated Document Object Model (DOM) can cripple website performance. It’s like trying to navigate a dense jungle – the more elements you have, the slower and more frustrating it becomes. But fear not, fellow web warriors! There are effective strategies to tame this DOM beast and unleash the speed your WordPress site deserves.

In this comprehensive guide, we’ll dive deep into understanding what DOM size is, why it matters, and, most importantly, how to fix excessive DOM size in WordPress. We’ll cover 11 proven techniques, from optimizing plugins and themes to implementing lazy loading and optimizing your database.

Get ready to equip yourself with the knowledge and tools to conquer this common WordPress challenge and deliver a seamless user experience for your visitors.

What Does the ‘Avoid an Excessive DOM Size’ Warning Mean?

If you’ve ever run a website speed test on your WordPress site and encountered a warning like “Avoid an excessive DOM size,” you’re not alone. This warning, often seen in tools like Google Lighthouse, Google PageSpeed Insights, or GTMetrix, signals that your website has too many elements, which can hinder its loading speed.

But what exactly is the DOM, and why does its size matter? Let’s break it down.

DOM Explained: Your Website’s Tree Structure

Think of your WordPress site as a sprawling tree structure. Each element on your page – text headings, images, menus, buttons – is like a branch or a leaf on this tree. These individual elements are called DOM nodes. The total number of nodes in your website’s tree structure is its DOM size.

The more elements you have on your page, the larger the DOM tree becomes. A simple page with just a heading and a paragraph might have a smaller DOM size compared to a complex page with multiple sections, images, contact forms, and embedded content.

Why DOM Size Matters for Website Performance

An excessive DOM size can have a detrimental impact on your website’s performance. When a browser encounters a page with a large DOM, it takes longer to read, understand, and load the structure. This is because a complex DOM structure requires more memory usage and processing power from the user’s device to display the page.

Here’s why DOM size is crucial:

• Slower Loading Times: A large DOM leads to slower loading times, which can frustrate visitors and cause them to bounce off your site before they even see your content. In today’s fast-paced digital world, users expect websites to load quickly. A slow-loading website can be like waiting in a long line – it discourages people from sticking around.
• Negative Impact on User Experience: A slow-loading website negatively impacts user experience, leading to higher bounce rates and lower engagement. This can ultimately harm your website’s overall success.
• SEO Implications: Search engines like Google prioritize websites that offer a good user experience, including fast loading speeds. A large DOM can indirectly hurt your WordPress SEO and, ultimately, website conversions.

How Many DOM Elements Are Too Many for Google?

While there’s no universally agreed-upon limit, Google Lighthouse and other testing tools flag websites with an excessive DOM size. Here’s a breakdown of what these flags might indicate:

• Warning: Google Lighthouse flags a warning when the body element of your page has more than approximately 800 nodes.
• Error: If the body element reaches over 1,400 nodes, Lighthouse throws an error.

Let’s put this into context to understand what kind of websites might fall into these categories.

• Websites with a Warning: Without proper optimization, a single page with text content, images, a navigation menu, basic layout elements, and multiple plugins for forms or social sharing could easily reach around 800 nodes.
• Websites with an Error: Pages exceeding 1,400 nodes are likely more complex and might include a higher number of elements. These can include multiple sliders or carousels with large images, elaborate layouts with many nested elements and sections, or multiple embedded content.

Remember, these are just general examples. Don’t let these illustrations scare you from building a custom website the way you want to. However, if you want to ensure people stay on your site, then you will need to avoid excessive DOM size.

11 Proven Ways to Fix Excessive DOM Size in WordPress

Now that you understand the importance of DOM size, let’s dive into the practical strategies to reduce it. Here are 11 effective tips you can implement to optimize your WordPress website:

1. Use a WordPress Speed Optimization Plugin

Our first recommendation is to install a powerful WordPress speed optimization plugin. These plugins are designed to analyze your website and make it faster in various ways. They can take care of the technical stuff needed to speed up your website, allowing you to focus on managing and creating your content.

Here at WPBeginner, we recommend using WP Rocket. We use it ourselves on the WPBeginner website, and it’s a powerful tool for boosting page load speed.

While WP Rocket is primarily known as a caching plugin, it has many features that can help with DOM size as well, including:

• File optimization: WP Rocket can minify CSS and JavaScript files, reducing their size and the number of HTTP requests your website needs to make.
• Lazy loading: WP Rocket can delay the loading of non-critical elements like images and videos until they are in the user’s view.
• Deferring JavaScript: WP Rocket can tell the browser to load some JavaScript files after the main content of your website has been displayed, resulting in faster initial page load times.

Using a speed booster plugin like WP Rocket is a great first step towards fixing DOM size and making your website faster, even if you’re new to WordPress.

2. Check Your Theme and Plugins

While WordPress plugins and themes are fantastic for adding functionality and style to your WordPress website, they can sometimes contribute to an excessive DOM size. Not all themes and plugins are created equal. Poorly-coded plugins and themes can result in a bloated HTML document with unnecessary elements.

Here are some things to keep in mind:

• Unnecessary Features: WordPress themes and plugins often come with extra features that you may not need. These features can add unwanted elements to your website’s structure, even if you are not actively using them.
• Reputable Sources: When choosing themes and plugins, stick with reputable sources like the WordPress directory or well-known developers. These resources have strict coding standards, reducing the chance of bloated code that could harm your website’s performance.

To identify potential culprits contributing to DOM size, take a closer look at what’s installed on your website. If you think a particular theme or plugin might be causing issues, try temporarily switching to a default WordPress theme or deactivating plugins one at a time. Then, see if the DOM size warning disappears in speed testing tools after making these changes. This can help you pinpoint the problematic element.

3. Use an Optimized Page Builder

Page builder plugins are WYSIWYG editors used for creating beautiful and functional WordPress websites without needing to code. However, some of these tools can contribute to an excessive DOM size.

Here’s why:

• Additional HTML Elements: Page builders often use additional HTML elements, like div tags with custom classes or attributes, to style your content and control its layout. While these elements allow for flexibility, they can also add a lot of bloat.
• Built-in Blocks and Widgets: Built-in blocks or widgets, like sliders or interactive elements created with a page builder, are often built using specific HTML structures that can contribute to DOM size.
• Shortcodes: Many page builders rely on shortcodes to insert their functionalities. While these shortcodes might not be visually displayed on your website, they can add extra code to your DOM behind the scenes.

If you think your page builder might be contributing to DOM size issues, test this theory on a staging site. Try deactivating your page builder and see if the warning disappears in website speed testing tools. This can help you determine if it’s the root cause.

If you decide to not use your old page builder anymore, then you can use one of the built-in WordPress tools to design your website (like the Full-Site Editor or Theme Customizer). They offer control over your website design without needing a separate plugin. They also typically have a smaller impact on DOM size.

However, these tools are not the most flexible. In this case, we recommend using an optimized page builder like SeedProd. Here at WPBeginner, we’ve tested various page builders, and SeedProd has shown faster performance compared to competitors.

4. Optimize Your Images and Videos

Unoptimized images and videos can have large file sizes. These large files can contribute to DOM size because they become extra elements the browser needs to process.

Here’s how to optimize your media:

• Image Optimization: Optimizing your images can significantly reduce their file size without sacrificing quality. This helps your website load faster and improves the overall user experience. A plugin like Optimole is a great solution for optimizing your images. Optimole is designed to work out of the box, automatically optimizing your website’s images as you upload them. You can also use free online tools like TinyPNG to compress your images before uploading them to your WordPress website.
• Video Hosting Services: When it comes to videos, we don’t recommend uploading them directly to WordPress. Large video files can significantly slow down your website’s loading time. A better approach is to use a video hosting service like YouTube or Vimeo. These services handle storing and streaming your videos, taking the load off your website’s server and reducing DOM size. You can then embed the videos directly into your pages using embed codes provided by the hosting service.

5. Implement Lazy Loading

Lazy loading is a technique that delays the loading of non-critical elements, like images and videos, until they are actually needed by the user as they scroll down the page. This means the essential content that appears first (like text and layout) loads faster, resulting in a quicker initial page load and a smoother user experience.

Setting up lazy loading is easy, especially if you’re already using a WordPress speed optimization plugin like WP Rocket. Simply navigate to Settings » WP Rocket in your WordPress dashboard. Then, click on the ‘Media’ tab. Here, just check off all the options for enabling lazy loading for images, videos, and iFrames.

If you want to display an image gallery, then we recommend using a gallery plugin with a lazy loading feature. Envira Gallery is a great example of this.

Additionally, you can lazy load your comments section. For this, you can use Thrive Comments, which offers features to optimize WordPress comments.

6. Paginate Comments or Posts With Lots of Content

Excessively long posts or comment sections typically have a large DOM size that can slow down your website’s loading times. Here’s where pagination comes in handy. Pagination essentially splits your content into manageable chunks, making it easier for users to navigate and digest information.

If you find yourself writing in-depth articles, consider splitting them into logical sections using pagination. This allows readers to take breaks between sections and avoid feeling intimidated by a giant wall of text. Luckily, you can easily break up long posts using the ‘Page Break’ block in the block editor.

We also have a helpful guide on how to paginate comments in WordPress. But essentially, all you need to do is log in to your WordPress admin area and go to the Settings » Discussions page. Then, check the box next to ‘Break comments into pages’ and customize the number of comments you want to see on each page.

Also, we suggest avoiding infinite scroll. While they can keep people on your site longer as they won’t have to switch between pages manually, this can cause performance issues on your server.

7. Minify CSS and JavaScript Files

Your website’s functionality and visual style rely on code files like CSS and JavaScript. While essential, these files can contribute to a larger DOM size if not properly optimized. Minification can solve this issue by removing unnecessary elements from the code, such as comments, spaces, and line breaks. This smaller size translates to faster loading times and a smaller DOM size.

It’s important to note that minification can sometimes introduce compatibility issues with certain themes or plugins. Before minifying your code, it’s a good idea to create a backup of your website and test the changes in a staging or local environment if possible. This allows you to identify any potential issues before they affect your live website.

Minifying your code is easy if you’re already using a plugin like WP Rocket. All you need to do is go to Settings » WP Rocket and switch to the ‘File Optimization’ tab. Then, just enable the features to minify CSS and JavaScript files.

Some WordPress hosting providers also offer built-in features for minifying CSS and JavaScript files. For instance, SiteGround offers the Speed Optimizer plugin to minify CSS.

8. Reduce Render-Blocking JavaScript and CSS

Another approach to optimize CSS and JavaScript files is by reducing render-blocking. Render-blocking resources are like foundation materials that prevent the house (your website content) from being built until those resources are delivered and in place. The longer it takes for these resources to load, the longer it takes for users to see your website’s content.

WP Rocket has built-in features to reduce render-blocking CSS and JavaScript. For example, you can combine CSS and JavaScript files, which will reduce the number of HTTP requests your website needs to make. Fewer requests mean less waiting time for the browser to load everything and render your content.

You can also remove any CSS code that isn’t actually used on your pages. This not only reduces render blocking but also minimizes overall page size and the number of HTTP requests.

Additionally, there is a feature called ‘Load JavaScript Deferred.’ This tells the browser to wait on loading some JavaScript files until after the main content of your website (the HTML) has been displayed. This way, users see your website’s content faster, even if all the background functionalities haven’t loaded yet.

9. Enable WordPress Caching

Caching doesn’t directly reduce DOM size, but it significantly improves your website’s perceived performance. Here’s what happens when caching is enabled: when a user revisits your website, their browser can check its cache first. If the files are already stored locally, they can be loaded much faster, significantly reducing page load times. This makes the DOM load and display faster, resulting in a smoother experience for visitors.

Caching also helps your server run more efficiently by lightening its workload. This frees it up to focus on important tasks like processing the DOM, which ultimately speeds up your loading time.

Fortunately, setting up browser caching is simple with a plugin like WP Rocket. This is because the plugin automatically enables caching with optimal settings for your website.

10. Use a WordPress CDN

A CDN (Content Delivery Network) is a network of servers spread out around the world. While a CDN doesn’t directly change the size of your website’s code, it makes your website feel like it loads faster. This is because a CDN stores copies of your website’s static content (images, scripts, stylesheets) on servers in different locations. When someone visits your website, their computer downloads the content from the CDN server closest to them. This significantly cuts down on download times compared to fetching everything from your original server, which might be far away. This faster delivery makes processing the DOM much faster.

Plus, a CDN helps your original server work faster by sharing the content delivery load. This allows the server to focus on what matters most, like processing the DOM. In turn, this makes your website render quicker overall.

We use Cloudflare’s CDN on our website here at WPBeginner. It works well for our large blog with lots of visitors.

11. Optimize Your WordPress Database

Your WordPress website relies on a database to store all its important information, like posts, comments, user accounts, and even configurations. Over time, this database can hold too much unnecessary data, such as old revisions of posts, spam comments, or leftover information from deleted plugins.

While the database itself isn’t part of the DOM, a bloated database can slow down your website. A slower website can make it seem like the DOM size is larger because everything takes longer to load and render. Optimizing your database by removing unnecessary data helps your website run smoother and can indirectly improve perceived DOM size.

Conclusion

Optimizing DOM size in WordPress is a critical step towards achieving lightning-fast website performance. By implementing the strategies outlined in this guide, you can significantly reduce your website’s loading times, improve user experience, and boost your SEO rankings. Remember, a well-optimized website is a happy website, and happy websites attract more visitors, leads, and conversions.

If you’re interested in learning more about tech news, feel free to visit my website: www.naveedahmed.me.

FAQs

What is the ideal DOM size for a WordPress website?

There’s no magic number for an ideal DOM size, but a general guideline is to aim for under 1,000 DOM nodes. However, the ideal DOM size will vary depending on the complexity of your website, its content, and the features you offer.

How can I check my website’s DOM size?

You can check your website’s DOM size using various website speed testing tools like Google Lighthouse, Google PageSpeed Insights, or GTMetrix. These tools will analyze your website’s performance and flag any issues related to excessive DOM size.

Is a large DOM always a bad thing?

Not necessarily. A website with a lot of functionality or unique formatting may naturally have a bigger DOM. The key is to find the right balance between site performance and features.

How does using a CDN affect DOM size?

A CDN doesn’t directly reduce DOM size, but it can make your website feel like it loads faster. This is because it delivers content from servers closer to your visitors, resulting in faster download times and a smoother experience.

Can I optimize my DOM size without using plugins?

While plugins can make the process easier, you can optimize DOM size without using plugins. This involves manually minifying CSS and JavaScript files, implementing lazy loading, and optimizing images and videos. However, plugins like WP Rocket offer a more comprehensive and efficient approach.

What are Core Web Vitals, and why are they important?

Core Web Vitals are a set of metrics that Google uses to measure a website’s user experience. They include Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). Optimizing Core Web Vitals is crucial for improving your website’s performance and SEO rankings.

Can a bloated database affect my DOM size?

While the database itself isn’t part of the DOM, a bloated database can slow down your website. A slower website can make it seem like the DOM size is larger because everything takes longer to load and render.

What is the difference between minification and render-blocking?

Minification reduces the size of CSS and JavaScript files by removing unnecessary characters, while render-blocking refers to resources that prevent the browser from displaying content until they are fully loaded.

Can lazy loading be applied to everything on my website?

Lazy loading is primarily used for non-critical elements like images and videos. It’s not recommended for essential content that needs to be loaded immediately, such as the website’s header or navigation menus.

Should I always aim for the fastest possible loading speeds?

While fast loading speeds are essential, it’s important to strike a balance between performance and functionality. If you need to include complex features that might increase loading times, it’s okay. The key is to optimize those features as much as possible to minimize their impact on performance.