Media library and concrete image instance
Check whether the image block uses a suitable image size or loads the original. A smaller original does not save a transmission size.
The alt text in the media library does not have to be the only value: a block or builder can store its own text and image size. Therefore, examine the image used in the article and the delivered img edition.
Where to check the setting in WordPress
Select the specific image instance in the article and compare its alt text with the data set in the media library. For own PHP output, wp_get_attachment_image can provide sizes and responsive sources; a hard-coded img tag does not automatically use this output.
Example of this specific finding
Illustrative control case: A product tile with 360 CSS pixels wide loads the 4,000 pixels wide original. What matters is the variant loaded in the network protocol, not the file name in the CMS.
follow-up audit in WordPress
After correcting image URL, check alternative text and selected responsive variant. A global media change does not use as proof that all existing blocks have been updated.
For multiple screen widths, check the selected image URL, file size and sharpness. On high-resolution displays, higher natural resolution may make sense.
Derogations and scope
A detailed view with Zoom may require larger files than a preview list. Balancing quality and transmission effort against actual use.
Related: WordPress with classic or block theme. SEO plugins and page builders are different; there is no universal menu path for all installations.
Classify the general error
Definition, system-independent causes and further correction examples: Check image weight, output size and subject together
Configuration and test signal documentation
WordPress: Image output with sizes and attributes