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Analyzing the Root Causes of a Slow WordPress Site and Best Practices for Optimization

The tangible risks of slow websites and the causes: themes, plugins, web hosting, large media files, data clutter, no caching, no CDN, too many redirects, outdated PHP.    

A one-second page loading delay leads to a 16% drop in customer satisfaction and an 11% drop in page views. It also causes a conversion rate decline of 7%. 

The bounce rate is just 32% if the website loads in three seconds or less. 

A recent survey by Kissmetrics found that 47% of internet users expect a maximum loading time of two seconds. If a site takes more than three seconds to load, 40% of users will abandon it. 

Response times are measured by Google’s Page Speed Insights. The scores range from 0 to 100. A 90+ score, translating to under 2.5 seconds, is considered good. A score of 50-90 corresponds to 2.5-4 seconds, which needs improvement. Anything below 50 is equivalent to four seconds or more. 

Leading causes of a slow WordPress site in 2024 

Themes with a lot of features and poor coding practices can significantly slow down your WordPress site. Each plugin adds code, which can increase loading times. Poorly coded plugins can also cause performance issues. This WordPress tutorial for beginners provides insight into some WordPress-specific issues.  

Outdated plugins and themes

Always keep your plugins and themes updated and delete any you’re not using. Unused themes and plugins harm website performance and present security vulnerabilities.

To remove a plugin, you must deactivate it first. Then, you can delete it from the list of inactive plugins. 

Feature-rich themes are appealing, but they come with a lot of code, which visitors to your site load every time. If your site is slow, use a minimalistic theme with basic but sufficient functions. You can delete unused WordPress themes under Appearance > Themes.

Web hosting quality

WordPress sites using shared hosting share resources with other websites. This can lead to slow performance if the server is overloaded. 

If your server is located far from your target audience, it can increase latency and slow down your site. 

Consider upgrading to VPS hosting and choosing a local hosting provider with servers nearby. 

Large media files

Hosting videos directly on your server can consume a lot of bandwidth. It’s better to embed videos from platforms like YouTube or Vimeo. 

Large image files are detrimental to page loading speed. You can compress images, create an image sitemap, and add alt text and titles. Remove images you aren’t using to free up space. Use a plugin to remove unused media or do it manually under Add Media -> Media Library -> Unattached.

Database optimization

Over time, data accumulates and clutters databases, driving website speed down. Regular cleanups can help the site load faster. 

Excessive post revisions and drafts can bloat your database and slow down queries. Consider this: a post of 100KB revised three times wastes 300 KB. You can clean your database manually through phpMyAdmin, but this requires technical knowledge. Running a plugin like WP-Sweep will get rid of spam comments, old revisions, MySQL queries, etc. 

High traffic volume, no caching 

A sudden surge in traffic can overwhelm your server, especially if you’re on a shared hosting plan. Caching stores static webpage versions and serves them to visitors instead of processing the same information repeatedly.

If caching is not properly configured, your site will serve outdated content or won’t utilize the cache effectively.

Make sure there’s an expiration date in your HTTPS headers so the browser doesn’t get old network resources from their local machine by mistake. 

Third-party scripts

Embedding too many third-party scripts, such as ads, social media widgets, or analytics tools, can increase loading times.

Not using a Content Delivery Network.

A CDN can distribute your content across multiple servers worldwide, reducing load times for visitors from different geographic locations. Not using a CDN can lead to slower load times for distant users.

Too many redirects

Redirect chains can significantly slow down the time it takes for a page to load.  It’s best to reduce the amount of information requests undertaken by the server.  

Outdated PHP

Running an older PHP version slows down websites and leads to missed improvements from newer versions. You can update to the latest PHP version via your WP Engine user portal.


What are the effects of a slow site? 

It ruins user experience, lowers search engine rankings, reduces website traffic, harms sales and conversion, and increases the bounce rate.  

Do you need a plugin to optimize WordPress site speed? 

No. You can speed up your site by optimizing all images in your media library and JS, CSS, and HTML files with minification and loading them as required only.