- Using HTTP features 304 not modified, expires header, keep-alive, gzip
- Reducing HTTP requests
- Caching images in browser
- Gzip Compression
- Proper CSS Placements
- Proper JavaScript placement
- Minimizing CSS and JavaScript code
- Serving images from cookie less domain
- Avoiding HTTP redirection
- Optimizing Ajax
- Use PHP accelerators
JavaScript Placement: JavaScript files have become important part of most of the web. Browsers allow parallel connections to a single hostname. This allows files to download faster in parallel and very helpful for web application performance. When JavaScript file is called browsers halts the parallel connections to all hosts. This is because JavaScript can alter the document dom with document.write(). more
This can badly hurt the front end performance of a web application. To avoid this all calls to JavaScript files should be moved to bottom of the page, just before end to BODY tag.
CSS Placement: A CSS file or style should be placed in HEAD element of the page. It is important because browsers render page progressively if CSS is placed in HEAD. Putting CSS at bottom can block progressive rendering in most of the browsers. more
Reducing HTTP Requests: A web page have multiple objects like images, css, JavaScript and flash etc. Browser have to send one http request to the server for each object. Each request adds a round trip to the server. Server have to receive and process each request and send the response.
For enhancing web application performance the rule is simple, reduce http requests.
- Combining Images
- Combining CSS files
- Combining JS files
- Using browser cache for performance
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