Question 1

How to use the HTTP/2 protocol to improve page resource loading efficiency?

Accepted Answer

When it is necessary to improve page resource loading efficiency, the HTTP/2 protocol achieves optimization through core features such as multiplexing and header compression. Based on the binary framing layer, it allows parallel transmission of multiple resources over a single TCP connection, reducing the overhead of connection establishment and maintenance.

Specific optimization methods include:
- Multiplexing: Simultaneously transmitting resources such as HTML, CSS, and JS within the same con

Question 2

How to reduce page blocking by optimizing CSS and JavaScript?

Accepted Answer

When a page loads, CSS and JavaScript may cause loading delays by blocking rendering or parsing. Targeted optimization can effectively reduce blocking and improve page loading performance.

CSS Optimization:
- Inline critical styles: Extract the CSS necessary for above-the-fold rendering and inline it into the HTML head to avoid external CSS files blocking the rendering path.
- Asynchronously load non-critical CSS: For non-above-the-fold styles (such as print styles), use media="print" or rel="p

Question 3

How much does server geographical location affect website response speed?

Accepted Answer

In general, the geographical location of a server has a significant impact on website response speed, especially when the physical distance between the user and the server is large, which can significantly increase data transmission latency.

The specific impacts are reflected in three aspects:  
- Physical distance: The farther the user is from the server, the longer the data transmission time in the network, directly leading to page loading delays (e.g., latency may increase by more than 100

Question 4

How to monitor and optimize TTFB (Time to First Byte) metrics?

Accepted Answer

When monitoring and optimizing the Time to First Byte (TTFB) metric, it is usually necessary to identify the source of delays using professional tools and then reduce response time through server configuration, resource management, and other means. TTFB is a core metric for measuring server response speed and directly affects user experience and search engine rankings.

**Monitoring Tools and Methods**:  
- Basic Detection: Browser developer tools (the "TTFB" field in the Network panel) allow re

Question 5

After a website enables HTTPS, how to ensure that performance is not negatively affected?

Accepted Answer

When migrating a website from HTTP to HTTPS, the negative impact on performance can be effectively avoided by optimizing TLS configuration, upgrading network protocols, and managing resources appropriately.

TLS Configuration Optimization: Select the TLS 1.3 protocol with modern cipher suites (such as ChaCha20/Poly1305) to reduce handshake steps; enable session reuse (Session Tickets or Session ID) to avoid repeated verification and reduce connection establishment time.

Protocol Upgrade: De

Question 6

How to detect and resolve Cumulative Layout Shift (CLS) issues on a page?

Accepted Answer

When detecting Cumulative Layout Shift (CLS) issues on a page, it is usually necessary to combine tool monitoring with code optimization. Detection can be done by generating CLS scores and element shift data via Lighthouse, recording shift events in real-time using Chrome DevTools' Performance panel, or tracking the overall site performance through Google Search Console's Core Web Vitals report.

The core of solving CLS issues is to reduce unexpected layout changes:  
- Specify dimensions: Set w

Question 7

What are the core reasons for the increased bounce rate due to poor mobile user experience?

Accepted Answer

When mobile terminals have problems such as slow loading, unreasonable interface design, or content adaptation issues, poor user experience directly leads to an increase in the bounce rate. The core reasons mainly include four aspects: loading performance, interaction design, content presentation, and navigation logic.

Loading performance: If the page loading time exceeds 3 seconds, users tend to lose patience and leave due to waiting; images or videos are not compressed, resulting in high traf

Question 8

How to optimize the first screen display speed of a page by preloading resources?

Accepted Answer

When optimizing the first screen display speed of a page, preloading critical resources is an effective method. By preloading core resources necessary for the first screen (such as critical CSS, first-screen images, and core JS), resource request delays are reduced, thereby accelerating first-screen rendering.

During implementation, it is first necessary to identify first-screen critical resources through performance analysis tools (such as Lighthouse) to distinguish between essential and non-e

Question 9

What are the application differences between Lazy Load and Intersection Observer in website performance optimization?

Accepted Answer

When optimizing website loading performance, Lazy Load is a strategy for delaying the loading of non-critical resources, while Intersection Observer is a technical tool to implement this strategy. There are core differences between the two in terms of positioning and application scenarios.

Positioning and Nature: Lazy Load is a performance optimization strategy whose core goal is to reduce the amount of initially loaded resources, loading resources (such as images and videos) only when they e

Question 10

How to optimize website performance to meet Google Page Experience requirements?

Accepted Answer

When optimizing website performance to meet Google Page Experience requirements, focus on improving Core Web Vitals metrics, ensuring mobile adaptability, guaranteeing safe browsing, and optimizing ad experience.

Core Web Vitals are the core evaluation dimensions: LCP (Largest Contentful Paint) should be controlled within 2.5 seconds, which can be achieved by compressing images/videos and using CDN to accelerate resource loading; INP (Interaction to Next Paint) should be below 200 milliseconds,

Question 11

How to measure the improvement of user trust and SEO effectiveness by HTTPS?

Accepted Answer

When evaluating the improvement of HTTPS on user trust and SEO effectiveness, it can be comprehensively measured through user behavior data and search engine performance indicators. As a security protocol, the impact of HTTPS on trust and SEO needs to be analyzed in combination with specific scenarios.

User trust indicators: The user attention rate of browser security indicators (such as the lock icon in the address bar), which can be observed through click or stay behavior using heat map tools

Question 12

How to ensure website performance and response speed when server load is too high?

Accepted Answer

When server load is too high, ensuring website performance and response speed requires starting from three aspects: traffic distribution, resource optimization, and load management. System stability is achieved by reasonably distributing requests, reducing invalid loads, and enhancing processing capacity.

Load balancing: Distribute traffic to multiple servers through load balancing devices or software (such as Nginx, HAProxy) to avoid single-point overload, suitable for scenarios with large tra

Question 13

How to accelerate global user access experience through CDN?

Accepted Answer

When it is necessary to accelerate the access experience for global users, a CDN (Content Delivery Network) reduces latency and improves loading speed by storing content on globally distributed edge nodes, thereby shortening the physical distance between users and data.

The specific implementation methods include:  
- Node coverage: Deploy edge nodes in user-concentrated areas to cover major target markets (such as North America, Europe, Southeast Asia, etc.), ensuring that users obtain conte

Question 14

For mobile devices, how to avoid loading delays caused by triggering large network requests?

Accepted Answer

When mobile applications or web pages need to handle a large number of network requests, the core of avoiding loading delays lies in optimizing resource size and request efficiency. Typically, strategies such as resource compression, request merging, and on-demand loading can effectively reduce network transmission volume and the number of requests, thereby lowering latency.

Resource compression: Compress images and CSS/JS files, such as using WebP format images and code minification to reduce

Question 15

How to optimize website performance to improve FID (First Input Delay) in Core Web Vitals?

Accepted Answer

When optimizing website performance to improve FID (First Input Delay) in Core Web Vitals, the core is to reduce main thread blocking time and ensure that user interactions can be quickly responded to by the browser. FID measures the delay from the user's first interaction (such as clicking a button) to the browser starting to process it, which is mainly affected by the busyness of the main thread.

Optimization directions include:
- JavaScript execution optimization: Remove unused code (e.g., T

Question 16

What are the possible performance issues and solutions during the issuance and renewal of HTTPS certificates?

Accepted Answer

When HTTPS certificates are issued or renewed, performance issues such as issuance delays, server load fluctuations, and domain validation failures may occur, which can usually be resolved through advance planning, optimizing the validation process, and selecting appropriate certificate types.

Issuance delay issue: The certificate application remains uncompleted for a long time, mostly due to complex CA review processes or incomplete verification information. Solutions: Choose CAs that support

Question 17

How to optimize the first screen loading speed for Single Page Applications (SPAs)?

Accepted Answer

When optimizing the first-screen loading speed of a Single-Page Application (SPA), focus on resource loading efficiency and rendering priority, and achieve improvements by reducing the initial loading volume, optimizing the loading order, and increasing rendering speed.

Resource volume control: Use code splitting (such as Webpack's dynamic import) to split non-first-screen code and only load initially necessary modules; compress images (using WebP/AVIF formats) and implement lazy loading to red

Question 18

What is the difference between responsive design and adaptive design in mobile performance optimization?

Accepted Answer

When optimizing mobile performance, the core difference between responsive design and adaptive design lies in their layout adaptation methods and resource loading strategies. Responsive design achieves "one codebase for multiple devices" through CSS media queries and fluid layouts, while adaptive design predefines multiple fixed layouts and matches the corresponding version based on device characteristics.

The performance optimization focus of responsive design is **dynamic adaptation cost**:

Question 19

How to use browser caching mechanisms to reduce repeated resource loading?

Accepted Answer

When the browser caching mechanism is properly configured, there is no need to re-download stored resources during repeated visits to a website, thereby reducing redundant loading. This goal is typically achieved by setting HTTP cache headers, resource versioning, and negotiation-based validation.

The main methods include:  
- Configuring the Cache-Control header: Set a long max-age (e.g., 31536000 seconds) for static resources (such as images, CSS/JS) to implement long-term caching; set no-c

Question 20

How to avoid page loading delays caused by overly long redirect chains?

Accepted Answer

When a website has excessively long redirect chains (such as multiple 301/302 redirects), it usually increases page loading time. This delay can be avoided by simplifying the redirect path and pointing directly to the final target URL.

Specific measures include: 1. Merge multi-level redirects, directly adjusting the chain "URL A→URL B→URL C" to "URL A→URL C"; 2. Remove unnecessary intermediate jumps, such as expired marketing campaign links or updated page paths; 3. Prioritize server-side redir

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