Report Summary

  • 79

    Performance

    Renders faster than
    86% of other websites

  • 87

    Accessibility

    Visual factors better than
    that of 67% of websites

  • 75

    Best Practices

    More advanced features
    available than in
    36% of websites

  • 79

    SEO

    Google-friendlier than
    40% of websites

cds.cern.ch

CERN Document Server

Page Load Speed

3.4 sec in total

First Response

773 ms

Resources Loaded

2.5 sec

Page Rendered

147 ms

cds.cern.ch screenshot

About Website

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Key Findings

We analyzed Cds.cern.ch page load time and found that the first response time was 773 ms and then it took 2.6 sec to load all DOM resources and completely render a web page. This is a poor result, as 50% of websites can load faster.

Performance Metrics

cds.cern.ch performance score

79

Measured Metrics

name

value

score

weighting

FCP (First Contentful Paint)

Value2.0 s

84/100

10%

LCP (Largest Contentful Paint)

Value2.9 s

80/100

25%

SI (Speed Index)

Value4.4 s

74/100

10%

TBT (Total Blocking Time)

Value200 ms

90/100

30%

CLS (Cumulative Layout Shift)

Value0.248

50/100

15%

TTI (Time to Interactive)

Value4.2 s

85/100

10%

Network Requests Diagram

cds.cern.ch

773 ms

PTSansWeb.css

758 ms

invenio.css

447 ms

cern_theme.css

423 ms

toolbar.css

181 ms

Our browser made a total of 22 requests to load all elements on the main page. We found that 77% of them (17 requests) were addressed to the original Cds.cern.ch, 14% (3 requests) were made to Framework.web.cern.ch and 9% (2 requests) were made to Piwik.web.cern.ch. The less responsive or slowest element that took the longest time to load (888 ms) relates to the external source Framework.web.cern.ch.

Page Optimization Overview & Recommendations

Page size can be reduced by 208.1 kB (56%)

Content Size

371.0 kB

After Optimization

162.8 kB

In fact, the total size of Cds.cern.ch main page is 371.0 kB. This result falls beyond the top 1M of websites and identifies a large and not optimized web page that may take ages to load. 20% of websites need less resources to load. Javascripts take 290.1 kB which makes up the majority of the site volume.

HTML Optimization

-81%

Potential reduce by 33.4 kB

  • Original 41.4 kB
  • After minification 36.2 kB
  • After compression 8.0 kB

HTML content can be minified and compressed by a website’s server. The most efficient way is to compress content using GZIP which reduces data amount travelling through the network between server and browser. This page needs HTML code to be minified as it can gain 5.2 kB, which is 12% of the original size. It is highly recommended that content of this web page should be compressed using GZIP, as it can save up to 33.4 kB or 81% of the original size.

Image Optimization

-16%

Potential reduce by 1.6 kB

  • Original 10.0 kB
  • After minification 8.4 kB

Image size optimization can help to speed up a website loading time. The chart above shows the difference between the size before and after optimization. Obviously, Cds CERN needs image optimization as it can save up to 1.6 kB or 16% of the original volume. The most popular and efficient tools for JPEG and PNG image optimization are Jpegoptim and PNG Crush.

JavaScript Optimization

-57%

Potential reduce by 166.4 kB

  • Original 290.1 kB
  • After minification 290.1 kB
  • After compression 123.7 kB

It’s better to minify JavaScript in order to improve website performance. The diagram shows the current total size of all JavaScript files against the prospective JavaScript size after its minification and compression. It is highly recommended that all JavaScript files should be compressed and minified as it can save up to 166.4 kB or 57% of the original size.

CSS Optimization

-23%

Potential reduce by 6.8 kB

  • Original 29.5 kB
  • After minification 29.5 kB
  • After compression 22.8 kB

CSS files minification is very important to reduce a web page rendering time. The faster CSS files can load, the earlier a page can be rendered. Cds.cern.ch needs all CSS files to be minified and compressed as it can save up to 6.8 kB or 23% of the original size.

Requests Breakdown

Number of requests can be reduced by 11 (58%)

Requests Now

19

After Optimization

8

The browser has sent 19 CSS, Javascripts, AJAX and image requests in order to completely render the main page of Cds CERN. We recommend that multiple CSS and JavaScript files should be merged into one by each type, as it can help reduce assets requests from 6 to 1 for JavaScripts and from 7 to 1 for CSS and as a result speed up the page load time.

Accessibility Review

cds.cern.ch accessibility score

87

Accessibility Issues

Contrast

These are opportunities to improve the legibility of your content.

Impact

Issue

High

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

Names and labels

These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.

Impact

Issue

High

Form elements do not have associated labels

Best Practices

cds.cern.ch best practices score

75

Areas of Improvement

Trust and Safety

Impact

Issue

High

Does not use HTTPS

High

Includes front-end JavaScript libraries with known security vulnerabilities

Low

Ensure CSP is effective against XSS attacks

General

Impact

Issue

Low

Detected JavaScript libraries

SEO Factors

cds.cern.ch SEO score

79

Search Engine Optimization Advices

Language and Encoding

  • Language Detected

    EN

  • Language Claimed

    EN

  • Encoding

    UTF-8

Language claimed in HTML meta tag should match the language actually used on the web page. Otherwise Cds.cern.ch can be misinterpreted by Google and other search engines. Our service has detected that English is used on the page, and it matches the claimed language. Our system also found out that Cds.cern.ch main page’s claimed encoding is utf-8. Use of this encoding format is the best practice as the main page visitors from all over the world won’t have any issues with symbol transcription.

Social Sharing Optimization

Open Graph description is not detected on the main page of Cds CERN. Lack of Open Graph description can be counter-productive for their social media presence, as such a description allows converting a website homepage (or other pages) into good-looking, rich and well-structured posts, when it is being shared on Facebook and other social media. For example, adding the following code snippet into HTML <head> tag will help to represent this web page correctly in social networks: