clinicaltrials.gov

Failed

Site speed report for https://clinicaltrials.gov based on real user browsing data from Google Chrome, sourced from Chrome User Experience Report (CrUX).

Core Web Vitals Assessment

This website fails the Core Web Vitals assessment. It will pass when Core Web Vitals are recorded as good for 75^th percentile of site visitors.

Largest Contentful Paint

2.36 sec

Good

View report

Cumulative Layout Shift

0.79

Poor

View report

Interaction to Next Paint

141 ms

Good

View report

Core Web Vitals history for clinicaltrials.gov

An in-depth look at Core Web Vitals performance.

Largest Contentful Paint

2.36 sec

Good

Largest Contentful Paint (LCP) measures how quickly the largest above-the-fold image, video or text element appears.

Largest Contentful Paint

When primary content is visible

improving

Last 3 months 75th percentile

LCP Experience

Largest Contentful Paint distribution by user experience

Last 3 months By user experience

LCP Resource Type

Breakdown of LCP resource types

Last 28 days

text

94.7 %

image

5.3 %

Last 3 months By resource type

LCP Image load timings

Breakdown of LCP image load timing subparts

Last 28 days

Time to First Byte

668 ms

Resource Load Delay

283 ms

Resource Load Duration

267 ms

Element Render Delay

181 ms

Last 3 months Image load subparts

Cumulative Layout Shift

0.79

Poor

Reduce CLS by 0.69 to reach "Good".

Cumulative Layout Shift (CLS) measures the visual stability of a page.

Cumulative Layout Shift

Page layout shifts

degrading

Last 3 months 75th percentile

CLS Experience

Cumulative Layout Shift distribution by experience

Last 3 months By user experience

Interaction to Next Paint

141 ms

Good

Interaction to Next Paint (INP) measures the time from the first input event to the next paint.

Interaction to Next Paint

Delays following user interaction

stable

Last 3 months 75th percentile

INP Experience

Interaction to Next Paint distribution by user experience

Last 3 months By user experience

Additional key metrics

These metrics are not categorised as Core Web Vitals, but are worth tracking to ensure a good user experience.

Time to First Byte

433 ms

Good

Time to First Byte (TTFB) measures the time taken for the first byte of a server response to arrive.

Time to First Byte

Initial server response delay

degrading

Last 3 months 75th percentile

TTFB Experience

Time to First Byte distribution by user experience

Last 3 months By user experience

First Contentful Paint

844 ms

Good

First Contentful Paint (FCP) measures the time taken for the first content to appear on the screen.

First Contentful Paint

When content appears on screen

improving

Last 3 months 75th percentile

FCP Experience

First Contentful Paint distribution by user experience

Last 3 months By user experience

Audience summary

Contextual metrics that describe how audiences experience clinicaltrials.gov.

Round Trip Time

110 ms

Round Trip Time (RTT) measures internet round trip time experienced by your users.

Round Trip Time

Latency experienced by your audience

stable

Last 3 months 75th percentile

RTT Experience

Round Trip Time distribution by user experience

Last 3 months By user experience

Devices

Types of devices used by your audience

Last 28 days

desktop

70.4 %

tablet

0.0 %

phone

29.6 %

Last 3 months By device type

Navigation types

Method used by your audience to navigate your site

Last 28 days

navigate

90.2 %

navigate cache

0.0 %

reload

4.2 %

restore

1.8 %

back forward

1.8 %

back forward cache

0.0 %

Last 3 months By navigation type

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CrUX Dashboard showing the Core Web Vitals assessment status, Largest Contentful Paint and Cumulative Layout Shift charts and values

Your questions answered

Where does this data come from?

Your summary is generated based on Google’s Chrome User Experience Report (CrUX) —a public dataset of real user experiences for millions of websites. CrUX collects data only for Chrome browser users who opted in (excluding devices with the iOS operating system). The set is updated daily and aggregates the previous 28 days of data.

How do I read this report?

The Core Web Vitals Assessment section shows if your page or site passes Core Web Vitals assessment. The 75^th percentile means that 75% of recordings were lower than showcased Web Vitals values (e.g. 75% of page or site visitors had Largest Contentful Paint of 2.5s or less).

The overall values are categorised as good, to improve or poor. Below, with a breakdown of each metric performance, you can see the percentage of good and poor user experiences and determine where you should make improvements.

Why is there no data for my site?

Your site has to have enough traffic to be included in the CrUX report. New sites are added to the dataset every day, so keep checking in the future or try running a report on the entire domain. In the meantime, you can also monitor Core Web Vitals in Calibre!

How do Core Web Vitals impact SEO?

Google evaluates pages based on content, relevance, quality, engagement metrics and many other factors. Core Web Vitals are a page ranking signal for your pages. To maximise website performance and outrank competitors, ensure all Core Web Vitals meet the recommended thresholds for a superior user experience.

How can I improve Core Web Vitals?

There are numerous ways to improve Core Web Vitals. The best way is to continuously monitor site speed (with tools like Calibre) and follow actionable advice tailored to your context. If you don’t know where to start, read our Getting Started with Web Performance and get actionable advice for specific metrics, such as Largest Contentful Paint, Cumulative Layout Shift and Interaction to Next Paint.

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Screenshot of Core Web Vitals assessment in Calibre