Website Performance Optimization
A high-performing website does more than just load quickly—it enhances user experience, improves accessibility, boosts search engine rankings, increases conversion rates, and supports overall business success. However, maintaining top performance requires consistent monitoring to detect and address regressions before they impact users.
In this guide, we’ll explore key principles of Website Performance Optimization and why it matters. You’ll also discover practical tools, techniques, and metrics to help you evaluate and optimize your website’s speed and responsiveness.
What You’ll Learn:
How to analyze network request waterfalls
Common website performance pitfalls
Strategies for managing large web resources
Recommended tools for performance testing
How to effectively monitor performance over time
Optimization techniques for faster load times
The difference between page load and runtime performance
Page Load Performance vs. Runtime Performance; Website Performance Optimization
While both contribute to the overall user experience, page load performance and runtime performance address different stages of how a website behaves.
Page Load Performance; Website Performance Optimization
This refers to the speed at which your web page initially loads. During this stage, the browser makes several network requests to download resources such as HTML, CSS, JavaScript, images, and fonts. These activities can be visualized using a network request waterfall chart, which shows the order and duration of each resource load.
Key metrics for page load performance include:
Time to First Byte (TTFB): Measures how quickly the server responds to a request
First Contentful Paint (FCP): Time it takes for the first visible content to appear
Largest Contentful Paint (LCP): Time taken for the largest piece of content to become visible
Runtime Performance; Website Performance Optimization
Runtime performance assesses how responsive your site is after the initial page load. Even if all resources have downloaded, the user experience may still suffer if interactions are sluggish or delayed.
Key metrics include:
Interaction to Next Paint (INP): Measures responsiveness to user input
JavaScript Execution Time: Speed of script processing and rendering
Render Performance: How quickly the browser reflects visual changes on screen
Understanding Network Request Waterfalls; Website Performance Optimization
A network request waterfall is a visual timeline of how the browser loads each resource. It’s an essential tool for diagnosing slow load times, prioritizing critical assets, and spotting bottlenecks.
These charts often include a filmstrip view, which captures visual snapshots of how your site appears over time during the loading process—providing an intuitive look at the real user experience.
You can generate these charts using tools like our Website Speed Test, which simulates page loads in a controlled environment and visualizes network activity. For more advanced analysis, consider tools like DebugBear and your browser’s developer tools—both offer deep insights and work best when used together.
Performance Testing and Optimization; Website Performance Optimization
This performance report reveals important metrics and links to deeper data sources like:
Lighthouse reports
Waterfall request views
Filmstrip comparisons
These insights help you pinpoint areas for improvement and implement data-driven strategies to keep your site fast, efficient, and user-friendly.