Tools & Wizards About Us
nat.vu.nl screenshot

Report Summary

  • 27

    Performance

    Renders faster than
    47% of other websites

  • 85

    Accessibility

    Visual factors better than
    that of 60% of websites

  • 92

    Best Practices

    More advanced features
    available than in
    81% of websites

  • 85

    SEO

    Google-friendlier than
    56% of websites

nat.vu.nl

Department of Physics and astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam

Page Load Speed

5.6 sec in total

First Response

637 ms

Resources Loaded

4.7 sec

Page Rendered

279 ms

nat.vu.nl screenshot

About Website

Visit nat.vu.nl now to see the best up-to-date Nat Vu content for Netherlands and also check out these interesting facts you probably never knew about nat.vu.nl

The Department of Physics and Astronomy is world leading in research and teaching of physics at the interface of life- and medical/health sciences. Important topics include the study of photosynthesis...

Visit nat.vu.nl

Key Findings

We analyzed Nat.vu.nl page load time and found that the first response time was 637 ms and then it took 5 sec to load all DOM resources and completely render a web page. This is a poor result, as 70% of websites can load faster.

Performance Metrics

nat.vu.nl performance score

27

Measured Metrics

name

value

score

weighting

FCP (First Contentful Paint)

Value3.0 s

50/100

10%

LCP (Largest Contentful Paint)

Value12.1 s

0/100

25%

SI (Speed Index)

Value7.6 s

25/100

10%

TBT (Total Blocking Time)

Value2,290 ms

5/100

30%

CLS (Cumulative Layout Shift)

Value0

100/100

15%

TTI (Time to Interactive)

Value9.9 s

27/100

10%

Network Requests Diagram

nat.vu.nl

637 ms

index.aspx

379 ms

static

656 ms

ga.js

23 ms

theme_nat

735 ms

Our browser made a total of 34 requests to load all elements on the main page. We found that 85% of them (29 requests) were addressed to the original Nat.vu.nl, 6% (2 requests) were made to Google-analytics.com and 6% (2 requests) were made to Vu.nl. The less responsive or slowest element that took the longest time to load (2.1 sec) belongs to the original domain Nat.vu.nl.

Page Optimization Overview & Recommendations

Page size can be reduced by 171.7 kB (13%)

Content Size

1.3 MB

After Optimization

1.1 MB

  • HTML
  • Images
  • JavaScript
  • CSS

In fact, the total size of Nat.vu.nl main page is 1.3 MB. This result falls beyond the top 1M of websites and identifies a large and not optimized web page that may take ages to load. 25% of websites need less resources to load. Images take 1.2 MB which makes up the majority of the site volume.

HTML Optimization

-82%

Potential reduce by 39.2 kB

  • Original 47.7 kB
  • After minification 34.6 kB
  • After compression 8.4 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 13.1 kB, which is 28% 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 39.2 kB or 82% of the original size.

Image Optimization

-9%

Potential reduce by 100.7 kB

  • Original 1.2 MB
  • After minification 1.1 MB

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. Nat Vu images are well optimized though.

JavaScript Optimization

-49%

Potential reduce by 28.2 kB

  • Original 58.2 kB
  • After minification 57.4 kB
  • After compression 29.9 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 28.2 kB or 49% of the original size.

CSS Optimization

-77%

Potential reduce by 3.6 kB

  • Original 4.7 kB
  • After minification 3.0 kB
  • After compression 1.1 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. Nat.vu.nl needs all CSS files to be minified and compressed as it can save up to 3.6 kB or 77% of the original size.

Requests Breakdown

Number of requests can be reduced by 16 (52%)

Requests Now

31

After Optimization

15

  • Images
  • JavaScript
  • CSS

The browser has sent 31 CSS, Javascripts, AJAX and image requests in order to completely render the main page of Nat Vu. 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 as a result speed up the page load time.

Network Requests Diagram

nat.vu.nl

nat.vu.nl

637 ms

index.aspx

index.aspx

379 ms

static

static

656 ms

ga.js

ga.js

23 ms

theme_nat

theme_nat

735 ms

jquery.cycle.all.min.js

jquery.cycle.all.min.js

383 ms

ga-searchengines.js

ga-searchengines.js

428 ms

ga-links.js

ga-links.js

474 ms

colorbox.css

colorbox.css

357 ms

jquery.colorbox-min.js

jquery.colorbox-min.js

345 ms

body_bg.png

body_bg.png

259 ms

Zwaartekrachtsgolven_tcm208-751399.png

Zwaartekrachtsgolven_tcm208-751399.png

385 ms

Banner-PhysicsMaster_tcm208-267496.jpg

Banner-PhysicsMaster_tcm208-267496.jpg

374 ms

footer_vua_en_tcm208-14398.gif

footer_vua_en_tcm208-14398.gif

342 ms

defaultsprite.png

defaultsprite.png

676 ms

restyle_intranet_arrow.gif

restyle_intranet_arrow.gif

481 ms

logo_tcm208-72379.png

logo_tcm208-72379.png

588 ms

general_menu_separator.gif

general_menu_separator.gif

622 ms

topic_physics_groot_tcm208-244794.jpg

topic_physics_groot_tcm208-244794.jpg

1066 ms

arrow2.gif

arrow2.gif

623 ms

accordion_down_1.png

accordion_down_1.png

719 ms

accordion_down_2.png

accordion_down_2.png

869 ms

accordion_down_3.png

accordion_down_3.png

851 ms

Zd2E9abXLFGSr9G3YK2MsFzqCfRpIA3W6ypxnPISCPA.woff

Zd2E9abXLFGSr9G3YK2MsFzqCfRpIA3W6ypxnPISCPA.woff

191 ms

__utm.gif

__utm.gif

119 ms

border3.png

border3.png

729 ms

border4.png

border4.png

706 ms

loading.gif

loading.gif

818 ms

cookie-bar-bg.png

cookie-bar-bg.png

943 ms

topic_life_groot_tcm208-244797.jpg

topic_life_groot_tcm208-244797.jpg

1504 ms

topic_energy_groot_tcm208-244800.jpg

topic_energy_groot_tcm208-244800.jpg

1293 ms

topic_light_groot_tcm208-244804.jpg

topic_light_groot_tcm208-244804.jpg

2144 ms

topic_astro_groot_tcm208-244802.jpg

topic_astro_groot_tcm208-244802.jpg

1373 ms

print.css

print.css

261 ms

Accessibility Review

nat.vu.nl accessibility score

85

Accessibility Issues

ARIA

These are opportunities to improve the usage of ARIA in your application which may enhance the experience for users of assistive technology, like a screen reader.

Impact

Issue

High

[aria-*] attributes do not match their roles

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

Image elements do not have [alt] attributes

Best Practices

nat.vu.nl best practices score

92

Areas of Improvement

Trust and Safety

Impact

Issue

High

Does not use HTTPS

Low

Ensure CSP is effective against XSS attacks

General

Impact

Issue

Low

Detected JavaScript libraries

High

Missing source maps for large first-party JavaScript

SEO Factors

nat.vu.nl SEO score

85

Search Engine Optimization Advices

Content Best Practices

Format your HTML in a way that enables crawlers to better understand your app’s content.

Impact

Issue

High

Links do not have descriptive text

High

Image elements do not have [alt] attributes

Mobile Friendly

Make sure your pages are mobile friendly so users don’t have to pinch or zoom in order to read the content pages. [Learn more](https://developers.google.com/search/mobile-sites/).

Impact

Issue

High

Document uses legible font sizes

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 Nat.vu.nl 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 Nat.vu.nl 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

nat.vu.nl

Open Graph description is not detected on the main page of Nat Vu. 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: