Content item, sitepackage and delivered assets
Examine image processing and fluid output of the largest visible element. A large original can be transferred unnecessarily despite a small CSS representation.
Limit the bottleneck to a specific element or resource. In TYPO3 projects, sitepackage, content elements and extensions can independently bring in additional scripts or large media; cache emptying alone does not remove this burden.
Where to check the setting in TYPO3
Assign the affected resource to the sitepackage or an extension. Compare the HTML of a simple content page to the slow detail page. Then check fluid image output, integrated assets and cache behavior of the responsible component.
Example of this specific finding
Illustrative control case: The performance trace identifies the hero photo as an LCP element. His request starts only after a script, although the image should be visible immediately.
follow-up audit in TYPO3
Under the same measurement conditions, compare the affected side and a side without the suspicious element. After a change, cached and first uncached responses also differ.
Examine request start time, download time and render delay separately. Make image source findable early and check the selected size and prioritization.
Derogations and scope
The LCP element can change per device or view. Once measured, a value is not a complete picture of the field data.
Reference: TYPO3 13.4 with EXT:seo. For other major versions and own extensions, responsibilities may differ; check the actually installed output.
Classify the general error
Definition, system-independent causes and further correction examples: Determining the Largest Visible Element