Compression and Page Weight Findings: Shrink a Heavy Page

Short answer: Two findings in the speed area of a Site AI Audit report deal with size. “Text files are sent without compression” is a warning that appears when your server sends HTML, CSS and JavaScript without gzip or Brotli. “The home page weighs N MB” is a warning that appears when the home page is heavier than about 3 MB. The first is fixed in one server setting. The second is usually fixed by compressing images and removing files that the page does not need.

Why size matters on a phone

Every byte of a page has to travel from your server to the visitor’s phone, often over a mobile connection that is slower than your office line and sometimes metered. A page of 6 MB means a long wait for someone on a weak signal and a real cost for someone with a limited data plan. The audit’s explanation for the page weight finding says it plainly: large pages load slowly on mobile data and cost visitors money.

That is why size is checked separately from the Google speed score. The score is a combined measure, while the size findings point to the cause that you can act on directly. Two sites with the same score can have different problems, one with a slow server and one with a large hero image, and the findings tell you which is yours.

The compression finding in detail

The finding reads “Text files are sent without compression”. It appears when the page response has no content encoding and the page is larger than about 20 KB. The explanation in the report is that gzip or Brotli usually makes pages 60 to 80 percent smaller, and the advice is to turn on gzip or Brotli compression on the server.

Text compresses very well, because HTML, CSS and JavaScript are full of repeated words and patterns. A page that is 150 KB without compression can arrive as 30 KB with it. The browser unpacks the file instantly, so the cost to the visitor is nothing, while the saving on every request is large. It is one of the few speed improvements that is both significant and almost free.

How to turn compression on

The method depends on where your site is hosted:

Managed or shared hosting. Look for a speed or performance section in the hosting panel; compression is often a toggle. If you cannot find it, ask support to enable gzip or Brotli for text files.
WordPress with a caching plugin. Many caching plugins include a compression option, but the server setting is better when you can change it.
Your own server. Enable the compression module for your web server and list the types to compress: HTML, CSS, JavaScript, JSON, SVG and fonts that are not already compressed.
Behind a CDN. Most content delivery networks compress for you, but check that it is turned on and that the origin does not strip the encoding.

The guide to gzip and Brotli compares the two methods and shows how to enable them. After the change, run a new check; the finding should be gone. If it is still there, the setting may apply to some file types but not to your HTML, or a layer in front of your server is removing it.

The page weight finding in detail

“The home page weighs N MB” appears when the measured weight of the home page is above about 3 MB. The advice in the report is to compress images in modern formats such as WebP or AVIF and to remove unused files. The number comes from the Google measurement of the page as a phone loads it, so it includes everything: HTML, styles, scripts, fonts and images.

In almost every heavy page, images account for most of the weight. A single uncompressed photograph straight from a phone camera can be 4 or 5 MB. Next come scripts, especially from third parties such as chat widgets, maps, video embeds and tracking tools, and then fonts, particularly when many weights and styles are loaded.

Where the weight hides

To find the cause, open your home page in a browser, open the developer tools and look at the network panel sorted by size. You will usually see one of these patterns:

A few huge images. Resize them to the size they are displayed at, and save them in a modern format. See WebP, AVIF and JPEG compared.
A slider or gallery that loads every picture at once. Replace it with one image, or load the others when needed; see lazy loading images.
A background video. It can weigh more than the rest of the page together.
Many font files. Use fewer weights and subset the fonts.
Heavy third-party scripts. Remove the ones you no longer use.

The article on reducing page weight goes through each case, and the one on JPEG and WebP quality settings shows how far you can compress an image before the loss is visible.

What not to do

A few well-meant fixes make matters worse. Do not compress images so hard that they look blurry on a large screen. Do not remove all images from the home page to hit a number; a good photograph is often the best thing on a page. And do not rely only on a plugin that “optimises” images without checking the result: look at the numbers afterwards. The goal is a page that is light enough to load quickly and still looks good, not the smallest possible file.

How to check that the fix worked

After you make a change, clear any cache on your site and run the check again. For compression, the finding should disappear. For page weight, the finding disappears when the home page falls under the threshold, and the speed area should show a better score. Because each change has a clear and measurable effect, it is worth fixing in this order: compression first, because it is one switch, then the largest images, then scripts and fonts.

Remember that the finding refers to the home page. Other pages can be heavier. The report lists slow pages as a separate notice: pages that took over 2 seconds to load during the crawl. If you fix the home page and the notice remains, look at the pages named there.

Caching: the help for repeat visits

Compression and smaller images help every first visit. Caching helps the visits that follow. When the browser can keep your logo, styles and scripts for a while, a returning visitor downloads almost nothing. The audit’s advice for a low mobile score mentions turning on caching for this reason. Page weight findings and caching are two halves of the same job: make the first load small and make the later loads almost free.

Check the smaller pages too

The weight finding looks at your home page, but visitors land on other pages as well, especially from search. After fixing the home page, open your most visited blog post and your main product or service page in the developer tools and look at the size. If the same kind of problem is there, such as oversized images or a heavy embed, fix the template or the image habit and the improvement will reach every page.

A note on third-party scripts

Third-party scripts deserve a special mention, because they add weight you do not control. A review widget, a chat bubble, a social feed and an analytics tool may each pull in several files from other servers. Make a list of the scripts on your home page and ask of each one: does it earn its place? Removing one that nobody uses is the cheapest page weight reduction there is.

A worked example

A wedding photographer’s site shows a warning for the home page weighing 7.8 MB and another for text files sent without compression. The home page has a full-width gallery of twelve photographs, each about 600 KB. She does two things. First she asks her host to turn on compression, which takes one message. Second, she replaces the gallery on the home page with three images, each resized to 1600 pixels wide and saved as WebP at about 120 KB, and links to a separate gallery page for the rest. The home page now weighs 1.1 MB. The new check shows neither finding, and the mobile speed score has moved from the critical range to a warning, a clear improvement for a few hours of work.

To find out what your home page weighs, check your website with Site AI Audit. The check needs a free account; the plans unlock the full report, so you can see the finding and its fix.

The bottom line

Compression and page weight are two of the most direct speed wins. Turn on gzip or Brotli once, then shrink the images and remove the files you do not need from the home page. Run the check again to confirm the numbers.

FAQ

What size triggers the page weight finding?

The warning appears when the home page weighs more than about 3 MB as measured during the speed step of the check.

Is Brotli better than gzip?

Brotli usually compresses a little better, but either method clears the finding. Use whichever your server supports well.

Do images need compression on the server?

No. JPEG, PNG, WebP and AVIF files are already compressed. They need resizing and a good format, not server compression.

Why does the finding refer only to the home page?

The page weight measurement comes from the Google test of your home page. Pages that load slowly in the crawl are reported separately.

Will a CDN fix a heavy page?

A CDN delivers files faster, but it does not make them smaller. Compress images and remove unneeded files first.