The web page in question has a significantly heavy page size (in excess of 4Mb) which can result in slow download times.
Why is this important?
A hefty page size generally indicates an abundance of page elements or extremely large individual elements (for example, oversized or unoptimized images), which leads to a sizable network payload when a user accesses the website. This large amount of data must be fully downloaded and processed by the browser, delaying the page's display.
What does the Optimization check?
This Optimization will be activated for any internal URL that accumulated total network requests are beyond 4,096 KiB.
How do you resolve this issue?
In addressing pages with oversized payloads, your focus should be on the heftiest of your page resources, as they contribute most significantly to the total size.
You can reduce the page size through various optimizations such as:
Resizing images appropriately
Image compression or adopting modern image formats (e.g., WebP)
Postponing non-essential requests
Often, these techniques overlap with other Performance Optimizations, suggesting that by working on those other areas of optimization, you can also enhance your network payloads.
Ideally, your total page size should be maintained below 1,600 KiB. This figure is benchmarked against the max data volume theoretically downloadable via a 3G connection while still achieving less than 10 seconds for Time to Interactive.
Optimization of such resources typically requires a developer knowledgeable of the site's codebase and might necessitate utilization of diagnostic utilities such as Lighthouse.
The following examples and methodologies offer guidance:
The Lighthouse tool also pinpoints the largest page resources by file size:
<img src="path-to-your-optimized-image.png" alt="Descriptive text for the image">
Avoid enormous network payloads (Lighthouse documentation)