Website optimization is a critical factor in ensuring fast page load times, reducing bounce rates, and boosting SEO rankings. In the pursuit of speed, many WordPress site owners combine performance plugins like WP Rocket, Autoptimize, and LiteSpeed Cache, expecting stellar performance enhancements. However, this trio—when misconfigured—can create severe issues, particularly duplicate JavaScript loading, which can negatively affect a site’s performance and functionality.
TL;DR: Concurrent usage of WP Rocket, Autoptimize, and LiteSpeed Cache can lead to the same JavaScript (and sometimes CSS) files being minified, optimized, and loaded multiple times. This duplication can harm page speed, create JavaScript conflicts, and inflate your HTML source code unnecessarily. To prevent these issues, only one plugin should handle JavaScript optimization. We will guide you on what to disable to ensure proper functionality and maximum speed efficiency.
The Culprit: Plugin Overlap in JavaScript Handling
Each of these plugins is powerful in its own right, offering advanced features to improve site speed. However, the problem arises because all three of them include overlapping features such as:
- JavaScript Minification
- JavaScript Combination
- Deferred or Delayed JavaScript Execution
- Inline Script Optimization
When these functions are enabled simultaneously across multiple plugins, each plugin attempts to process the same files. As a result, the exact same JavaScript files can end up being loaded multiple times under slightly different filenames, such as:
- autoptimize_b123456.js
- rocket-min-js-b64e0c.js
- litespeed_opt_js_bg2333.js
This does not just duplicate JS file loading; it leads to increased DOM size, slower parsing by the browser, and potential clashes between multiple versions of the same script running simultaneously.
Recognizing the Symptoms
If you’re unsure whether this is affecting your site, here are tell-tale signs of JavaScript duplication:
- Pagespeed Insights showing more than one optimized version of the same JS file.
- Chrome Developer Console listing identical scripts under different paths.
- Unexpected JavaScript behavior such as duplicated sliders, broken tabs, or unresponsive menus.
- Large HTML source code with multiple versions of similar-looking minified files.
You might even notice worsening performance in page speed tools after enabling all three plugins rather than improvements.
How Each Plugin Handles JavaScript
To fully understand the issue, we need to look at what each plugin attempts to do in isolation:
WP Rocket
- Minifies and combines JavaScript files
- Offers deferred and delayed loading
- Preloads/caches scripts linked in content
Autoptimize
- Combines and minifies JS files with fine-grained control
- Injects optimized JS directly into HTML or as external files
- Has options for excluding certain scripts or folders
LiteSpeed Cache
- Deep integration with LiteSpeed servers for server-level optimization
- Minification and combination options similar to Autoptimize
- Provides QUIC.cloud CDN integration with JS cache layer
Each plugin attempts to handle the same job, which results in redundancy and interference if all are enabled simultaneously without careful configuration.
What You MUST Disable
To regain control and prevent duplicate JavaScript loading, follow these critical steps for configuration. You must decide which plugin will serve as your main JavaScript handler and disable overlapping features in the others.
Option 1: Let WP Rocket Handle JavaScript
If you choose to let WP Rocket manage JS optimization (recommended if you’re already a paying user), disable the following features in the others:
In Autoptimize:
- Uncheck ‘Optimize JavaScript Code’
- Uncheck ‘Aggregate JS-files’
In LiteSpeed Cache:
- Go to Page Optimization > JS Settings
- Disable ‘JS Minify’
- Disable ‘JS Combine’
- Disable ‘Load JS Deferred’
Option 2: Use Autoptimize Alongside WP Rocket (Advanced Users)
You may choose to let Autoptimize handle JavaScript and let WP Rocket focus on caching only. In that case:
In WP Rocket:
- Disable ‘Minify JavaScript Files’
- Disable ‘Combine JavaScript Files’
- Disable ‘Delay JavaScript Execution’
Note: Autoptimize and WP Rocket can work side-by-side, but it requires careful exclusions and consistent testing across your site. This is not recommended unless you are confident with debugging JS-related conflicts.
In LiteSpeed Cache:
- Again, turn off all JS optimization options
Option 3: Use LiteSpeed Cache Only (LiteSpeed Server Required)
If you host under a LiteSpeed server, consider switching fully to LiteSpeed Cache for all optimizations, as it integrates best with the infrastructure:
In WP Rocket:
- Disable all JavaScript handling
In Autoptimize:
- Disable JavaScript optimization features
Make use of LiteSpeed’s own CDN and optimization engine via QUIC.cloud for best results in this setup.
Best Practices and Recommendations
No matter which plugin you choose as your JavaScript optimizer, these universal practices apply:
- Avoid enabling the same optimization feature in multiple plugins.
- Clear all caches after making changes (including server, browser, and plugin caches).
- Test your site thoroughly on both desktop and mobile after adjusting settings using Chrome’s Developer Tools or Lighthouse.
- Use Pingdom or Google Pagespeed Insights to confirm no duplicate requests are made.
Each optimization layer adds complexity. Keep it simple: let one plugin do the heavy lifting when it comes to JavaScript.
Conclusion
WordPress optimization does not have to be a minefield. While combining WP Rocket, Autoptimize, and LiteSpeed Cache might appear to be a comprehensive performance strategy, the overlap of functionalities—particularly with JavaScript—can backfire disastrously. Redundant script loading not only delays rendering but also introduces bugs and bloated page sizes.
Trust the process: disable duplicate tasks, commit to a single optimization strategy, and carefully configure your chosen plugin. Monitor carefully, test thoroughly, and remember that more optimization is not always better—smarter optimization is.
By taking a mindful, consolidated approach, you’ll preserve both your site’s speed and its stability.