Why is your website loading slowly? Unveiling the 7 key factors affecting web performance

In today's digital era, website loading speed has become one of the key metrics for evaluating user experience and online success. Studies show that for every second of delay in page loading time, conversion rates may drop by 7% and bounce rates increase by 11%. So why is your website loading slowly? This article will systematically analyze the 7 key factors affecting web performance and provide practical optimization solutions.

1. The server response time is too long.

Server response time is the primary factor affecting website loading speed. When a user requests to access a webpage, the time it takes for the server to process the request and return the content directly impacts the Time to First Byte (TTFB). Slow server responses may be caused by the following reasons:

• Shared hosting resources are insufficient, with multiple websites competing for the same server resources.
• The server has low hardware specifications and cannot handle high-concurrency requests.
• The database query efficiency is low, especially for unoptimized WordPress sites.
• The server is geographically distant from the target user group.

SolutionConsider upgrading to a VPS or dedicated server, optimizing database queries, selecting a server geographically close to your target users, or utilizing edge computing technologies like Cloudflare Workers.

2. Unoptimized images and media files

Images are usually the largest components of a webpage, and unoptimized images can significantly slow down loading speed. Common issues include:

• Use high-resolution but uncompressed original images.
• Choosing an inappropriate image format (such as using PNG instead of JPEG)
• The image dimensions are much larger than the actual display requirements.
• Not using modern image formats such as WebP

Optimization strategyUse tools like TinyPNG to compress images, adjust them to appropriate dimensions before uploading, select the optimal format based on content (JPEG for photos, PNG for simple graphics, WebP for balancing quality and compression), and implement responsive image techniques (srcset attribute).

3. Excessive HTTP requests

Each CSS file, JavaScript file, image, and font requires a separate HTTP request, and browsers have a limit on the number of concurrent requests to the same domain (typically 6-8). Too many requests can lead to:

• The browser is queuing and waiting for the request to be processed.
• Increased DNS lookup and TCP connection overhead
• Extend the critical rendering path

Methods to reduce requests:Combine CSS and JavaScript files, use CSS Sprites to merge small icons, inline critical CSS, defer non-critical JavaScript loading (defer/async attributes), and use SVG icons instead of font icons.

4. Browser cache is not fully utilized

Browser caching allows repeat visitors to load resources from local storage instead of fetching them from the server every time. Improperly configured cache policies can lead to:

• Static resources (such as logos, CSS, JS) are repeatedly downloaded.
• Increasing server load and unnecessary bandwidth consumption
• Extend the full page loading time

Best practices for cachingSet long-term caching (e.g., 1 year) for static resources, use content hashing for cache busting, configure appropriate cache control headers (Expires, Cache-Control), and leverage Service Workers for offline caching (PWA).

5. Redundant and unoptimized code

Redundant and inefficient code in frontend code (HTML, CSS, JavaScript) can significantly impact parsing and execution time.

• Unused CSS rules and JavaScript code
• Rendering-blocking synchronous JavaScript
• Complex CSS selectors and deep nesting
• Uncompressed source code

Code optimization techniques:Regularly clean up unused code, use tree-shaking to remove unreferenced modules, place JavaScript at the bottom of the body or use defer/async, compress and obfuscate code, simplify CSS selectors, and avoid blocking caused by @import.

6. Third-party scripts and plugins

Modern websites often integrate various third-party services (analytics tools, advertisements, social media plugins, etc.), and these scripts are frequently performance bottlenecks.

• Third-party scripts usually come from third-party CDNs and are beyond your control.
• Many analysis/advertising scripts are large in size and inefficient in execution.
• Social media plugins may load the entire framework.
• Lack of control over the loading priority of these scripts

Manage third-party scriptsEvaluate the necessity of each third-party service, delay loading non-critical scripts, use asynchronous loading, set timeouts and fallback mechanisms, consider self-hosting commonly used libraries, and limit the number of third-party scripts loaded simultaneously.

7. Improper or missing CDN configuration

A Content Delivery Network (CDN) distributes content through a global network of servers, reducing latency caused by physical distance. Improper use of CDNs includes:

• No CDN is used, and all traffic relies on a single server.
• CDN configuration error, cache rules not taking effect
• Use CDN only for static resources, excluding HTML.
• Selected a CDN provider that is not suitable for the target user group.

CDN Optimization Recommendations:Configure appropriate CDNs for static resources and dynamic content, set correct cache headers, leverage edge computing features (such as edge caching, A/B testing), monitor CDN performance, and select providers with extensive global coverage (e.g., Cloudflare, Akamai).

Performance Optimization Checklist

By systematically diagnosing and addressing these 7 key factors, you can significantly improve your website's loading speed, enhance user experience, and consequently boost conversion rates and search engine rankings. Remember, website performance optimization is an ongoing process that requires regular monitoring and adjustments to adapt to the ever-evolving content and technological environment.