Many WordPress websites suffer from performance issues not because of server limitations, but because they load large amounts of unnecessary CSS and JavaScript on every page. As sites grow and additional plugins are added, frontend assets can quickly become bloated, increasing page weight, HTTP requests, and Core Web Vitals metrics such as Largest Contentful Paint (LCP).
This case study demonstrates how auditing and removing unused CSS significantly improved page speed and overall user experience.
Issue Background
A WordPress website was loading more than 344 KB of CSS on a high-traffic page, yet only a fraction of that code was actually being used by the browser. Additional plugin-generated JavaScript and stylesheets were also loading globally despite only being needed on a handful of pages.
The result was slower rendering, unnecessary network requests, and degraded performance scores in tools such as Google PageSpeed Insights and Lighthouse.
Diagnosis
A frontend performance audit identified several sources of unnecessary assets:
- WordPress core styles loading despite the site relying entirely on a page builder.
- Search & Filter Pro loading approximately 275 KB of CSS and JavaScript across the entire website.
- wpDataTables assets loading on pages where tables were not present.
- Slick Carousel styles loading globally.
- Magnific Popup assets loading despite not being used on target pages.
- Mega Menu assets loading on pages where advanced navigation functionality was not required.
Collectively, these assets created hundreds of kilobytes of unnecessary payload and numerous extra HTTP requests.
Resolution Steps
1. Audit loaded assets
Use browser DevTools, Lighthouse, GTmetrix, or PageSpeed Insights to identify CSS and JavaScript files loading on each page.
2. Remove unused WordPress core styles
Where appropriate, dequeue stylesheets that are not required by the site’s theme or page builder implementation.
3. Implement conditional asset loading
Configure plugins such as Search & Filter Pro to load assets only on pages where their functionality is needed.
4. Dequeue unused plugin styles
Prevent plugins such as wpDataTables, Slick Carousel, Magnific Popup, and Mega Menu from loading globally when they are not actively being used.
5. Test for functionality regressions
After removing assets, thoroughly test forms, navigation, search functionality, and interactive features to ensure nothing breaks.
6. Benchmark improvements
Re-run Lighthouse and PageSpeed tests to quantify the impact of optimization efforts.
Final Outcome
The optimization project removed approximately 538 KB of unnecessary CSS and JavaScript and eliminated 13 HTTP requests from uncached page loads.
Performance improvements included:
- Performance score improvement from 85 to 91.
- Largest Contentful Paint improvement from approximately 3.6 seconds to under 3 seconds.
- First Contentful Paint improvement from 2.9 seconds to approximately 2.6 seconds.
By reducing asset bloat and implementing conditional loading strategies, the website achieved faster rendering, improved Core Web Vitals, and a better user experience.
If you need help optimizing WordPress performance, reducing CSS bloat, configuring WP Rocket, improving Core Web Vitals, or troubleshooting plugin-related performance issues, contact Freshy.
