How to Boost the Performance of Your Website to Promote it in Search Engines – Fifth Part
Wednesday, October 14, 2009 2:06
A mechanism for browsers and servers to determine if the component that is in the browser’s cache is in match with the other on the origin server is entity tags of Etags. An Etag is used to identify and validate a specific version of webpage component. The origin server uses the Etag to specify the Etag of a component. The browser sends back the Etag to the origin server using the If-None-Match header. On matching of the Etags, a 304 status code returns and reduces the response by 12195 bytes.
Etags are unique to a particular server only when they are constructed using typical attributes. If the Etag on the original server and the Etag on a different server do not match, users do not receive the 304 response. Rather, they get a 200 response with the data for webpage component. It is not a serious problem, if your site is hosted on one server. If the website is hosted on multiple servers, your users will experience slower pages. Webpage components on websites with a higher load are not efficiently cacheable. Removing Etags is better to decrease the size of the HTTP headers in both requests and responses.
One of the much-practiced tactics to bolster the performance of websites is making Ajax cacheable. Providing instant feedback to users is one of the utilities of Ajax. It sends request for information from the backend web server. Using Ajax does not mean that users are not required to wait for the return of JavaScript and XML responses. If users are kept waiting depends on the use of Ajax in many applications. Optimizing the Ajax responses makes them cacheable. Gzipping components, reducing DNS lookups, minifying JavaScript, avoiding redirects and configuring Etags are the recommended techniques to boost the performance of Ajax.
A request from users for a page takes the backend server from 200 to 500ms to stitch the HTML page. While waiting for the data, the browser remains idle. One of the common functions in PHP is flush that enables the browser to fetch components by sending the partially ready HTML response to the browser. The place next to the HEAD of pages is the right to place flush because it is easier to produce the HTML for the HEAD. It also allows inclusion of JavaScript and CSS files for the browser.
JavaScript is ideal to boost the user experience. But without JavaScript, you can ensure the initial rendering of pages. Adding to the user experience is the use of post-load scripts that make it possible to have such options as drag and drop. Much opposite to post-load scripts, preload components are cacheable in the browser. When the browser is at rest, you can request for the components of next page by means of preloading components. When the user makes visit to the next page, the page will load faster than before. Preloading is of several types – unconditional preload, conditional preload and anticipated preload.
The plate is heaped with tips on speeding up website performance. So, be patience to wait for my next blog….
