Knowledge Base

Why Is My Website Slow?

There can be many reasons why your website is slow. Some of the most common reasons include:

• Large images: High-resolution images can significantly increase page load time.
• Unoptimized code: Poorly written or unnecessary code slows down the browser's processing of the page.
• Too many HTTP requests: The browser requesting many files (images, style sheets, scripts, etc.) from the server negatively impacts performance.
• Server issues: A slow or overloaded server affects the performance of your entire website.
• Lack of caching: Not using browser caching causes visitors to re-download all content even when revisiting the same page.
• JavaScript blocking: JavaScript code located at the top of the page that stops the browser can delay the page from being displayed.
• Not using a CDN: Not using a Content Delivery Network (CDN) can cause users to access your website from a distant server, leading to delays.

By eliminating these causes, you can significantly increase the speed of your website.

What is Google PageSpeed Insights and How to Use It?

Google PageSpeed Insights (PSI) is a free tool that analyzes the performance of web pages and provides improvement recommendations. PSI evaluates the speed of the page for both mobile and desktop devices and gives a score between 1 and 100. It also suggests specific fixes that can be implemented to improve performance.

To use PageSpeed Insights:

1. Visit the PageSpeed Insights website.
2. Enter the URL of the web page you want to analyze.
3. Click the "Analyze" button.
4. PSI will analyze the page's performance and give a score. It will also provide improvement recommendations.

The PSI report includes the following sections:

• Performance: A score showing the overall performance of the page.
• Opportunities: Things you can do to improve the page's loading time.
• Diagnostics: Additional information about issues that may affect performance.
• Passed Audits: Things the page is already doing well.

By following the recommendations provided by PageSpeed Insights, you can significantly increase the speed of your website.

Real-Life Example: An e-commerce site realized they hadn't optimized their images after a PageSpeed Insights analysis. After compressing and resizing their images, page load times decreased by 40% and conversion rates increased by 15%.

How Do I Optimize Images?

Image optimization is one of the most important steps to improve your website's speed. Large images can significantly impact page load time. You can use the following methods to optimize images:

• Choose the Image Format:
  • JPEG: Ideal for photographs. It uses lossy compression, which reduces file size but slightly reduces quality.
  • PNG: Ideal for logos, icons, and images requiring transparency. It uses lossless compression, which preserves quality but can result in larger file sizes compared to JPEG.
  • WebP: A modern image format that offers both lossy and lossless compression. It can provide better compression ratios than JPEG and PNG. It may not be supported by all browsers, so you may need to provide JPEG or PNG alternatives for backward compatibility.
  • AVIF: A next-generation format that provides even better compression than WebP. However, browser support is still limited.
• Compress Images: Compressing images helps reduce file size while maintaining visual quality. Many online image compression tools are available (TinyPNG, ImageOptim, Compressor.io, etc.).
• Resize Images: Resize images to the size they will be displayed on the web page. Reducing very large images eliminates unnecessary data load.
• Use Responsive Images: By providing different image sizes for different device sizes, ensure that each user receives optimized images suitable for their device. This can be implemented using the <picture> tag or the srcset attribute.

Example: Responsive images with the <picture> tag

<picture>
  <source media="(max-width: 600px)" srcset="image-small.jpg">
  <source media="(max-width: 1200px)" srcset="image-medium.jpg">
  <img src="image-large.jpg" alt="Description">
</picture>

This code will display "image-small.jpg" if the screen size is smaller than 600 pixels, "image-medium.jpg" if it is smaller than 1200 pixels, and "image-large.jpg" if it is larger.

How Do I Optimize JavaScript and CSS?

Optimizing JavaScript and CSS files is critical to improving your website's speed. Unoptimized JavaScript and CSS files can slow down the browser's processing of the page and increase page load time. Here are some methods for optimizing JavaScript and CSS:

• Minification: Reduce the file size by removing unnecessary characters (spaces, line breaks, comments, etc.) from JavaScript and CSS files. Many online minification tools (UglifyJS, CSSNano, etc.) or build tools (Webpack, Parcel, etc.) are available.
• Concatenation: Reduce the number of HTTP requests by combining multiple JavaScript or CSS files into a single file.
• Compression: Reduce the size of JavaScript and CSS files sent to the browser by enabling Gzip or Brotli compression on your server.
• Inline Critical CSS: Prevent the browser from downloading an external CSS file by placing the CSS required for the initial display of the page (critical CSS) directly into the HTML. Load the remaining CSS asynchronously.
• Load JavaScript Asynchronously or Deferred: Prevent the browser from blocking HTML parsing by loading JavaScript files with <script async> or <script defer> tags. async executes the script as soon as it is downloaded, while defer executes the script after HTML parsing is complete.
• Remove Unused CSS: Identify and remove unused CSS rules on your website. This reduces file size and helps the browser process less CSS.

Example: Loading JavaScript asynchronously

<script src="script.js" async></script>

This code will load the "script.js" file asynchronously. The browser will download the script while continuing to parse the HTML, and will execute the script when the download is complete.

How Do I Use Browser Caching?

Browser caching is an important tool for improving your website's performance. Browser caching stores static resources of the website (images, CSS files, JavaScript files, etc.) on the user's computer. When a user visits the same page again, the browser loads the resources from the cache instead of re-downloading them from the server. This significantly reduces page load time.

To use browser caching, you need to configure HTTP caching headers on your server. The most commonly used caching headers are:

• Cache-Control: Specifies how the cache should behave. For example, Cache-Control: max-age=3600 specifies that the resource can be cached for 3600 seconds.
• Expires: Specifies when the resource will become invalid.
• ETag: Specifies a unique identifier for the resource. The browser compares the ETag with the server before requesting the resource again.
• Last-Modified: Specifies the date the resource was last modified.

Example: Configuring caching using the .htaccess file in Apache

<FilesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|swf)$">
  Header set Cache-Control "max-age=604800, public"
</FilesMatch>

<FilesMatch "\.(css)$">
  Header set Cache-Control "max-age=1209600, public"
</FilesMatch>

<FilesMatch "\.(js)$">
  Header set Cache-Control "max-age=1209600, private"
</FilesMatch>

<FilesMatch "\.(xml|txt)$">
  Header set Cache-Control "max-age=604800, private, must-revalidate"
</FilesMatch>

<FilesMatch "\.(html|htm)$">
  Header set Cache-Control "max-age=0, private, must-revalidate"
</FilesMatch>

This code specifies different caching durations for different file types. For example, images and videos are cached for 604800 seconds (7 days), while CSS and JavaScript files are cached for 1209600 seconds (14 days).

What is a Content Delivery Network (CDN) and How to Use It?

A Content Delivery Network (CDN) is a network that stores your website's content on servers distributed around the world. When a user accesses your website, the CDN serves the content from the server closest to the user's geographic location. This significantly reduces page load times and improves the user experience.

Benefits of a CDN:

• Faster Load Times: CDNs reduce latency by serving content from servers closer to users.
• Better User Experience: Faster load times help users stay on your website longer and engage more.
• Reduced Server Load: CDNs reduce the load on your server, allowing your website to perform better.
• Better SEO: Google uses your website's speed as a ranking factor. Improving your website's speed using a CDN can improve your SEO performance.
• Security: CDNs often offer protection against DDoS attacks and other security measures.

Steps to Use a CDN:

1. Choose a CDN Provider: There are many CDN providers available, such as Cloudflare, Akamai, and Amazon CloudFront. Choose a provider that suits your needs and budget.
2. Integrate Your Website with the CDN: Integrate your website with the CDN by following the CDN provider's instructions. This usually requires you to change your DNS settings and use a domain name provided by the CDN provider.
3. Upload Your Content to the CDN: Upload your static content (images, CSS files, JavaScript files, etc.) to the CDN. Some CDNs automatically pull content from your server, while others require you to upload the content manually.
4. Configure the CDN: Configure the CDN's caching rules, security settings, and other options.
5. Test and Monitor: Test your website and monitor its performance to ensure that the CDN is working correctly.

How Do I Optimize Database Queries?

If your website uses a database, the performance of database queries can significantly affect page load time. Slow database queries can cause your website to slow down or even crash. You can use the following methods to optimize database queries:

• Indexing: Add indexes to frequently queried columns in database tables. Indexes help the database find data faster.
• Query Optimization: Optimize your SQL queries. Avoid selecting unnecessary data and use WHERE and JOIN statements correctly.
• Query Caching: Cache the results of frequently executed queries. This prevents the database from running the same query over and over again.
• Optimize Database Structure: Optimize the structure of your database tables. Remove unnecessary columns and choose data types correctly.
• Optimize Database Server: Optimize the configuration of your database server. Adjust memory settings, disk I/O settings, and other parameters correctly.

Example: Adding an index in MySQL

ALTER TABLE users ADD INDEX email_index (email);

This code will add an index to the "email" column in the "users" table. This will make queries based on the "email" column run faster.

How Do I Improve Server Response Time (TTFB)?

Server Response Time (Time to First Byte - TTFB) is the time it takes for the browser to receive the first byte from the server. TTFB is an important factor affecting the speed of your website. A high TTFB can cause your website to load slowly.

Ways to Improve TTFB:

• Choose a Better Hosting Provider: A quality hosting provider offers faster servers and better infrastructure.
• Optimize Your Server: Optimize your server's configuration. Properly adjust memory settings, disk I/O settings, and other parameters.
• Use Caching: Use caching on your server. Caching helps the server serve static content faster.
• Use a CDN: A CDN reduces latency by serving content from servers closer to users.
• Optimize Database Queries: Slow database queries can increase TTFB. Optimize your database queries.
• Use HTTP/2: HTTP/2 is a more efficient protocol than HTTP/1.1. HTTP/2 can send multiple requests in parallel and use compression.

Example: Caching configuration in Nginx

proxy_cache_path /tmp/nginx_cache levels=1:2 keys_zone=my_cache:10m max_size=10g inactive=60m use_temp_path=off;

server {
    location / {
        proxy_cache my_cache;
        proxy_cache_valid 200 302 60m;
        proxy_cache_valid 404 1m;
        proxy_pass http://backend;
        proxy_set_header Host $host;
    }
}

This code configures caching in Nginx. The cache is stored in the "/tmp/nginx_cache" directory and uses a key zone named "my_cache". Responses with HTTP status codes 200 and 302 are stored in the cache for 60 minutes, while responses with HTTP status code 404 are stored in the cache for 1 minute.

Why is Mobile Optimization Important?

Today, a large portion of internet traffic comes from mobile devices. Therefore, it is critical that your website runs quickly and smoothly on mobile devices. Mobile optimization is a series of actions taken to improve the user experience of your website on mobile devices.

Benefits of Mobile Optimization:

• Better User Experience: A fast and smooth website on mobile devices helps users stay longer and interact more.
• Higher Conversion Rates: A good mobile experience can increase conversion rates. Mobile users can more easily shop or fill out forms on a mobile-friendly website.
• Better SEO: Google lists mobile-friendly websites higher in search results. Mobile optimization can improve your SEO performance.
• Lower Bounce Rate: A slow or unusable mobile website can cause users to leave immediately. Mobile optimization can reduce the bounce rate.

Mobile Optimization Techniques:

• Responsive Design: A design approach that ensures your website automatically adapts to different screen sizes.
• Mobile Speed Optimization: Optimize images, minify JavaScript and CSS, use caching, and use a CDN to ensure your website loads quickly on mobile devices.
• Touch-Friendly Interface: Design a touch-friendly interface so that your website can be easily used on mobile devices. Use large buttons and easily readable text.
• Mobile-First Indexing: Google uses the mobile version of your website as the primary source for indexing. Make sure your mobile website contains all the important content.

How to Increase My Google PageSpeed Insights Score?

The Google PageSpeed Insights (PSI) score is an indicator of your website's performance. A high PSI score indicates that your website is fast and user-friendly. You can follow the steps below to increase your PSI score:

1. Analyze the PSI Report: Carefully analyze the PSI report and identify the problems mentioned.
2. Implement the Recommendations: Implement the recommendations mentioned in the PSI report. Optimize images, minify JavaScript and CSS, use caching, use a CDN, and apply other optimization techniques.
3. Test Again: After making the changes, test your website again with PSI and make sure your score has increased.
4. Continue to Improve: Continuously monitor your website's performance and continue to improve it.

Case Study: A news site realized that it had not optimized JavaScript and CSS files after PageSpeed Insights analysis. After minifying and merging the files, the PSI score increased from 55 to 85, and page load times decreased by 30%.

Important PageSpeed Optimization Metrics and Target Values

Other Tools You Can Use to Test Your Website's Speed