User Experience Performance Single Region Diagnostic Results

Webpage: https://www.simon.co.jp

Device: Desktop Computer

Region: Australia (Sydney)

Single Region Score

43
Poor Page Performance
A total of 21 improvements can achieve a better score
Serve images in next-gen formats

Image formats like WebP and AVIF often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. [Learn more about modern image formats].

Background and foreground colors do not have a sufficient contrast ratio.

Low-contrast text is difficult or impossible for many users to read. [Learn how to provide sufficient color contrast].

Reduce the impact of third-party code

Third-party code can significantly impact load performance. Limit the number of redundant third-party providers and try to load third-party code after your page has primarily finished loading. [Learn how to minimize third-party impact].

`[aria-*]` attributes do not have valid values

Assistive technologies, like screen readers, can't interpret ARIA attributes with invalid values. [Learn more about valid values for ARIA attributes].

Does not have a `<meta name="viewport">` tag with `width` or `initial-scale`

A `` not only optimizes your app for mobile screen sizes, but also prevents [a 300 millisecond delay to user input]. [Learn more about using the viewport meta tag].

Links do not have descriptive text

Descriptive link text helps search engines understand your content. [Learn how to make links more accessible].

Largest Contentful Paint element

This is the largest contentful element painted within the viewport. [Learn more about the Largest Contentful Paint element]

Links do not have a discernible name

Link text (and alternate text for images, when used as links) that is discernible, unique, and focusable improves the navigation experience for screen reader users. [Learn how to make links accessible].

ARIA toggle fields do not have accessible names

When a toggle field doesn't have an accessible name, screen readers announce it with a generic name, making it unusable for users who rely on screen readers. [Learn more about toggle fields].

Efficiently encode images

Optimized images load faster and consume less cellular data. [Learn how to efficiently encode images].

Avoid large layout shifts

These are the largest layout shifts observed on the page. Each table item represents a single layout shift, and shows the element that shifted the most. Below each item are possible root causes that led to the layout shift. Some of these layout shifts may not be included in the CLS metric value due to [windowing]. [Learn how to improve CLS]

LCP request discovery

Optimize LCP by making the LCP image [discoverable] from the HTML immediately, and [avoiding lazy-loading]

`[aria-*]` attributes do not match their roles

Each ARIA `role` supports a specific subset of `aria-*` attributes. Mismatching these invalidates the `aria-*` attributes. [Learn how to match ARIA attributes to their roles].

Image elements have `[alt]` attributes that are redundant text.

Informative elements should aim for short, descriptive alternative text. Alternative text that is exactly the same as the text adjacent to the link or image is potentially confusing for screen reader users, because the text will be read twice. [Learn more about the `alt` attribute].

Uses deprecated APIs

Deprecated APIs will eventually be removed from the browser. [Learn more about deprecated APIs].

Third parties

Third party code can significantly impact load performance. [Reduce and defer loading of third party code] to prioritize your page's content.

Elements with an ARIA `[role]` that require children to contain a specific `[role]` are missing some or all of those required children.

Some ARIA parent roles must contain specific child roles to perform their intended accessibility functions. [Learn more about roles and required children elements].

ARIA input fields do not have accessible names

When an input field doesn't have an accessible name, screen readers announce it with a generic name, making it unusable for users who rely on screen readers. [Learn more about input field labels].

Reduce unused JavaScript

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. [Learn how to reduce unused JavaScript].

Enable text compression

Text-based resources should be served with compression (gzip, deflate or brotli) to minimize total network bytes. [Learn more about text compression].

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