Performance Metrics
User Experience
Filmstrips
Time To First Byte
Time to First Byte (TTFB) is a web performance metric that represents the amount of time it takes for a user's browser to receive the first byte of data from a web server after making a request. In other words, TTFB captures the time it takes for the server to respond to the initial request and begin transmitting data.
TTFB is an important metric because it provides insights into how quickly a web server can process requests and deliver content. A faster TTFB results in a quicker website loading time and a better user experience.
TTFB can be affected by various factors, including server performance, network latency, and the size of the requested resource. Consequently, improving TTFB requires optimizing these factors, such as using a faster web server, reducing server processing time, or minimizing the size of resources.
First Contentful Paint
First Contentful Paint (FCP) is a Core Web Vitals metric that measures the time it takes for a user's browser to render the first piece of content on a web page. The content can be anything visible to the user, such as text, images, or videos.
FCP is an important metric because it gives website owners and developers insight into the perceived speed of their site from a user's perspective. A faster FCP results in a quicker loading time, and a better user experience.
FCP is influenced by various factors, including server response times, network latency, and the size of resources. Optimizing FCP requires minimizing these factors and ensuring that the page content is delivered as quickly as possible.
In summary, First Contentful Paint (FCP) is a Core Web Vitals metric that measures how quickly the first piece of content is displayed on a web page, providing critical insights into a user's perception of a site's loading speed and overall performance.
Speed Index
Speed Index is a performance metric that measures how quickly the content of a web page is visually displayed during the loading process. It represents the average time at which visible parts of the page are displayed to the user. A lower Speed Index score indicates a faster-loading page, leading to a better user experience.
Speed Index is calculated based on the visual progress of a page load, taking into account the area above the fold (the portion of the web page visible without scrolling). The metric captures the user's perceived loading experience and helps identify issues that may not be apparent when looking at other metrics like load time or Time to First Byte (TTFB).
In summary, Speed Index is an important performance indicator that helps developers and website owners understand how quickly their web pages are rendering for users, allowing them to optimize the site for better performance and improved user experience.
Largest Contentful Paint
Largest Contentful Paint (LCP) is a Core Web Vitals metric that measures the loading speed of the largest content element on a web page. The largest content element can be anything visible to the user, such as an image, video, or block of text.
LCP is an essential metric because it captures the time it takes for the most significant piece of content to become visible to the user. A faster LCP results in a quicker loading time and a better user experience.
LCP is influenced by various factors, such as server response times, network latency, and the size of resources. Improving LCP requires optimizing these factors to ensure that the largest content element on a page is delivered as quickly as possible.
In summary, Largest Contentful Paint (LCP) is a Core Web Vitals metric that measures how quickly the largest content element on a web page is displayed, providing insights into a site's overall performance and user experience.
Total Blocking Time
Total Blocking Time (TBT) is a Core Web Vitals metric that measures the total amount of time a web page is unresponsive to user input. TBT captures the duration between First Contentful Paint (FCP) and Time to Interactive (TTI), during which the user cannot interact with the page.
TBT is an important metric because it provides insights into how quickly a page becomes interactive and responds to user input, such as clicking or scrolling. A lower TBT score indicates that a page is more responsive to user input, leading to a better user experience.
TBT is influenced by various factors such as server response times, resource loading, and JavaScript execution. To improve TBT, developers can optimize these factors by minimizing render-blocking resources, reducing JavaScript execution time, and optimizing the critical rendering path.
In summary, Total Blocking Time (TBT) is a Core Web Vitals metric that measures the duration during which a page is unresponsive to user input and provides insights into a site's interactivity and responsiveness.
Cumulative Layout Shift
Cumulative Layout Shift (CLS) is a Core Web Vitals metric that measures the visual stability of a web page as it loads. CLS quantifies how much the page layout shifts while the user is interacting with the website, and it takes into account the size of each shift and the number of times it occurs.
CLS is an important metric because it captures how visually stable a page is during the loading process. A lower CLS score indicates that a page is less likely to cause unexpected layout shifts, leading to a better user experience.
CLS can be influenced by various factors such as images and iframes without dimensions specified, dynamically injected content, and web fonts. To improve CLS, developers can optimize these factors by setting dimensions for images and iframes, minimizing the use of dynamically injected content, and using font-display to control font loading.
In summary, Cumulative Layout Shift (CLS) is a Core Web Vitals metric that measures the visual stability of a page during the loading process and provides insights into a user's experience while interacting with the site.