WPBakery’s split CSS loading, introduced in version 9.0, divides its global stylesheet into element-specific styles and aims to load styles based on the content of each page. That can reduce unused CSS, but WPBakery’s published article does not provide the promised percentage-based test results, and enabling the feature is no guarantee of a faster site. The practical answer depends on your installed version, settings, extensions, and the pages you test.
What split CSS loading changes
In its September 2026 article, WPBakery describes the change this way: “instead of always loading one large CSS file, styles are now split by element and loaded only when needed.” The idea is to use a page’s content to determine which element styles to load, rather than sending one broad stylesheet to every page. WPBakery introduced the feature in version 9.0. WPBakery’s feature article and its 9.0 beta announcement describe the design and testing guidance.
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WPBakery’s stated rationale is that less unused CSS may mean less network transfer and less browser work. It says that “on most pages, up to 90%” of the CSS is unused. That is the vendor’s broad assertion in its 2026 article, not an independent measurement of every WPBakery site and not a reported result of the 9.0 split-loading test.
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It may help if a page previously received substantial CSS for elements it does not use. But the vendor article reports only preliminary reductions on pages with limited element sets. It says full percentage-based results would be published alongside the 9.0 release; the article does not include those results. It offers no independent performance study or comparative numeric results for the three modes.
So treat split loading as a change worth testing, not a guaranteed speed upgrade. The outcome can depend on which elements appear on a page, how the theme and custom elements enqueue styles, and whether other optimization tools alter or combine the CSS. A smaller stylesheet alone also does not establish a faster page: inspect actual requests, unused CSS, visual rendering, and the site’s own performance measurements.
Legacy, Hybrid, and Optimized modes
WPBakery’s article describes three CSS loading modes. It said Legacy remained the default when the article was published and that a future switch to Hybrid was planned. That statement is time-bound; it does not establish the default in every later release or installation. Check the settings available in your installed version before changing the mode. WPBakery’s settings documentation and release notes provide product context, but release notes about CSS splitting do not establish a universal current default.
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| Mode | What the cited article establishes | What to check on your site |
|---|---|---|
| Legacy | WPBakery identified it as the default when its September 2026 article was published. | Whether your installed version still uses it by default, how much CSS your representative pages receive, and whether existing styles remain intact. |
| Hybrid | WPBakery described it as an intended future default change. | Whether it is available in your version and how it behaves with your theme, extensions, and optimization tools. |
| Optimized | WPBakery named it as a mode, but the cited article gives no comparative numeric results for it. | Whether it reduces delivered or unused CSS on your pages without causing visual or compatibility problems. |
The article does not establish how much CSS each mode delivers in every configuration. Compare modes using the pages and components your site actually depends on rather than assuming the mode name predicts the result.
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How to evaluate it safely
WPBakery recommends testing different page types and custom elements. Use a staging site where possible, and compare the same pages under the old and new modes. Keep other optimization settings unchanged during the comparison so you can attribute differences more clearly.
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- Record your starting point. Note your WPBakery version and current CSS mode. Select representative pages, including a lean page and a complex page; add WooCommerce, portfolio, and custom-element pages if your site uses them.
- Change one setting at a time. Use the CSS mode control available in your installed WPBakery settings. The exact options and defaults may vary by version, so do not rely on a path or label from a different release.
- Compare stylesheet delivery. For the same pages, inspect browser network requests and an unused-CSS audit. Look at which stylesheets load and how much CSS is delivered, not just the number of files.
- Check visual integrity. Review the pages at initial load and after interactions. Look for missing element styles, layout changes, and flashes of unstyled content—the possibility WPBakery says it considered in its testing.
- Keep or revert based on the results. If a mode breaks a page or does not produce a useful improvement in your measurements, return to the previous setting and investigate interactions with theme styles, custom elements, or optimization tools.
What custom elements and WordPress styles mean for compatibility
Split loading does not establish automatic compatibility with every extension that adds a custom element. WPBakery recommends using standard WordPress enqueue functions and conditionally loading assets for custom elements. WordPress’s theme guidance also describes loading block styles only when those blocks are used; this platform-level approach is useful context, not proof that every custom extension integrates with WPBakery’s feature. See WPBakery’s asset-management documentation and the WordPress Theme Handbook’s block stylesheets guidance.
If a custom element loses styling after a mode change, check how its stylesheet is registered and enqueued, and whether it is loaded on the page where the element appears. Treat that as a compatibility issue to diagnose rather than assuming the split-loading feature will discover every extension’s assets automatically.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Should you enable it?
Test it if your pages load a substantial set of WPBakery styles that they do not use, and you can verify both performance and appearance on representative pages. Be more cautious on sites that rely heavily on custom elements, commerce flows, or CSS optimization tools, because those combinations need their own checks. WPBakery’s cited material explains the intended mechanism and testing considerations, but it does not establish a universal performance gain.
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