When evaluating a website, performance is a crucial aspect that encompasses several factors beyond just how quickly the site loads. Here’s a breakdown of the four key aspects of website performance—page speed, responsiveness, stability, and resource usage—along with their focus areas and key metrics.
Page Speed
Page speed refers to how quickly the content of a web page loads and becomes viewable to users. It’s a critical factor in user satisfaction and can significantly impact search engine rankings.
Key Metrics
- Page Load Time: Measures the total time it takes for a page to load completely from the moment a user requests it until all content is fully visible.
- Time to First Byte (TTFB): Indicates the time taken for the first byte of data to be received from the server. A lower TTFB means a faster response from the server.
- First Contentful Paint (FCP): The time it takes for the first piece of content (text or image) to appear on the screen.
Responsiveness
Responsiveness describes how well a website reacts to user interactions, such as clicks, taps, or scrolling. It reflects how smoothly and efficiently the site performs tasks in real time.
Key Metrics
- Time to Interactive (TTI): Measures the time it takes for the page to become fully interactive, meaning users can interact with all page elements without delays.
- Input Latency: Indicates the delay between a user action (e.g., clicking a button) and the website’s response to that action.
- Scroll Performance: Evaluates how smoothly the page scrolls, particularly during high-load operations or when large amounts of content are present.
Stability
Stability refers to how well a website performs under various conditions, including high traffic or resource constraints. It measures the reliability and consistency of the site’s performance over time.
Key Metrics
- Largest Contentful Paint (LCP): Measures the time it takes for the largest content element (e.g., an image or block of text) to become visible on the screen.
- Cumulative Layout Shift (CLS): Quantifies the amount of unexpected layout shift that occurs during the page load, which can affect user experience.
- Error Rate: Tracks the frequency of errors or issues encountered by users, such as broken links or failed requests.
Resource Usage
Resource usage pertains to how efficiently a website uses system resources such as memory and CPU. It evaluates how well the site manages and optimizes these resources.
Key Metrics
- Memory Usage: Monitors the amount of memory used by the website during operation, including for scripts and media files.
- CPU Usage: Measures the amount of CPU resources consumed by the website, which can impact server performance and scalability.
- Network Requests: Tracks the number and size of network requests made by the website, as a high number can lead to increased load times and resource consumption.
Website performance isn’t just about how fast a page loads. It also includes page speed, responsiveness, stability, and resource usage. Focusing on these factors ensures your site loads quickly and offers a smooth, reliable experience. For improving these key metrics, check out how to use Unlighthouse in this article.