10 Rules by Yahoo for high website speed | Lafandar.org

Do you think that website load time doesn't matter in SEO . Think twice do you know :-

A study found that second delay in load time produce the following results :-

1. 15% fewer page-views.
2. 20% decrease in the customer satisfaction.
3. 12% loss in conversion.

I have created a list 20 rules proposed by Yahoo which effects the website speed. You should lookup these rules to increase your website speed :-

1. Minimize HTTP Requests :- 

Most of the time spent in loading webpage is loading in  images, stylesheets, scripts, Flash, etc. Reducing the number of components in turn reduces the number of HTTP requests required to render the page. This is the key to faster pages.

One way to reduce the number of components in the page is to simplify the page's design.If your blog contains too much posts try to start campaign to optimize one page per day.

2.Reduce server response time :-

Your target is a server response time of less than 200ms (milliseconds). And if you follow the tips in this article, you’re well on your way to achieving this.

3. Enable compression for page elements :-

Large pages (which is what you could have if you’re creating high-quality content) are often 100kb and more. As a result, they’re bulky and slow to download. The best way to speed their load time is to zip them—a technique called compression.

Compression reduces the bandwidth of your pages, thereby reducing HTTP response. You do this with a tool called Gzip.

Most web servers can compress files in Gzip format before sending them for download, either by calling a third-party module or using built-in routines. According to Yahoo, this can reduce download time by about 70%.

And since 90% of today’s Internet traffic travels through browsers that support Gzip, it’s a great option for speeding up your site.

4.Prioritize the page content :-

Having just recommended that you use only one CSS stylesheet and no inline CSS, there is one caveat you need to consider. You can improve user experience by having your above-the-fold (top of the page) load faster—even if the rest of the page takes a few seconds to load.

5.Reduce DNS lookup :-

The Domain Name System (DNS) maps hostnames to IP addresses, just as phonebooks map people's names to their phone numbers. When you type www.lafandar.org into your browser, a DNS resolver contacted by the browser returns that server's IP address. DNS has a cost. It typically takes 20-120 milliseconds for DNS to lookup the IP address for a given hostname. The browser can't download anything from this hostname until the DNS lookup is completed.

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DNS lookups are cached for better performance. This caching can occur on a special caching server, maintained by the user's ISP or local area network, but there is also caching that occurs on the individual user's computer. The DNS information remains in the operating system's DNS cache (the "DNS Client service" on Microsoft Windows). Most browsers have their own caches, separate from the operating system's cache. As long as the browser keeps a DNS record in its own cache, it doesn't bother the operating system with a request for the record.

6. Avoid Page Redirects :-

Redirects are accomplished using the 301 and 302 status codes. Here's an example of the HTTP headers in a 301 response:

      HTTP/1.1 301 Moved Permanently
      Location: http://example.com/newuri
      Content-Type: text/html

The browser automatically takes the user to the URL specified in the Location field. All the information necessary for a redirect is in the headers. The body of the response is typically empty. Despite their names, neither a 301 nor a 302 response is cached in practice unless additional headers, such as Expires or Cache-Control, indicate it should be. The meta refresh tag and JavaScript are other ways to direct users to a different URL, but if you must do a redirect, the preferred technique is to use the standard 3xx HTTP status codes, primarily to ensure the back button works correctly.

The main thing to remember is that redirects slow down the user experience. Inserting a redirect between the user and the HTML document delays everything in the page since nothing in the page can be rendered and no components can start being downloaded until the HTML document has arrived.

7. Remove duplicate scripts :-

It hurts performance to include the same JavaScript file twice in one page. This isn't as unusual as you might think. A review of the ten top U.S. web sites shows that two of them contain a duplicated script. Two main factors increase the odds of a script being duplicated in a single web page: team size and number of scripts. When it does happen, duplicate scripts hurt performance by creating unnecessary HTTP requests and wasted JavaScript execution.

8.Make Ajax Cacheable :-

One of the cited benefits of Ajax is that it provides instantaneous feedback to the user because it requests information asynchronously from the backend web server. However, using Ajax is no guarantee that the user won't be twiddling his thumbs waiting for those asynchronous JavaScript and XML responses to return. In many applications, whether or not the user is kept waiting depends on how Ajax is used. For example, in a web-based email client the user will be kept waiting for the results of an Ajax request to find all the email messages that match their search criteria. It's important to remember that "asynchronous" does not imply "instantaneous".

9. Flush the buffer early :-

When users request a page, it can take anywhere from 200 to 500ms for the backend server to stitch together the HTML page. During this time, the browser is idle as it waits for the data to arrive. In PHP you have the function flush(). It allows you to send your partially ready HTML response to the browser so that the browser can start fetching components while your backend is busy with the rest of the HTML page. The benefit is mainly seen on busy backends or light front-ends.

Read :- 10 SEO Tips for Your Website ?

A good place to consider flushing is right after the HEAD because the HTML for the head is usually easier to produce and it allows you to include any CSS and JavaScript files for the browser to start fetching in parallel while the back-end is still processing.

Example:

      ... <!-- css, js -->
    </head>
    <?php flush(); ?>
    <body>
      ... <!-- content -->

10.No 404s:-

HTTP requests are expensive so making an HTTP request and getting a useless response (i.e. 404 Not Found) is totally unnecessary and will slow down the user experience without any benefit.

Some sites have helpful 404s "Did you mean X?", which is great for the user experience but also wastes server resources (like database, etc). Particularly bad is when the link to an external JavaScript is wrong and the result is a 404. First, this download will block parallel downloads. Next the browser may try to parse the 404 response body as if it were JavaScript code, trying to find something usable in it.