How to improve web applications performance - Best Practices

Best Practice to improve the performance of web application:

Practice 1 :
Minimize HTTP Request
More than 70% response time is spent on downloading front end contents like style sheets, images, scripts, flash etc. It means less the contents, less the HTTP requests and better performance:

Followings are good way to minimize the HTTP request:
a)Try to combine all CSS into single style sheet for whole application.
b)Try to combine all scripts into one single script file.
c)Prefer to put image URLs with cached CSS rather than page itself (This will decrease the page size)
d)Try to combine multiple images into one image, let say your back ground is combination of images then better create on image file which will reduce the hits to server to download small images each time. This only works if the images are contiguous in the page, such as a navigation bar.
Above mentioned all tricks will reduce the number of HTTP request and as a result will feel better performance of site.

Practice 2 :
Use Compression
Compression reduces response times by reducing the size of the HTTP response. Gzip is the most popular and effective compression method currently available and generally reduces the response size by about 70%. Approximately 90% of today's Internet traffic travels through browsers that claim to support gzip.
There are lot of compression filters available to use this trick:) with j2ee enabled web applications

Practice : 3
Use Expire headers
Web pages are becoming increasingly complex with more scripts, style sheets, images, and Flash on them. A first-time visit to a page may require several HTTP requests to load all the components. By using Expires headers these components become cacheable, which avoids unnecessary HTTP requests on subsequent page views. Expires headers are most often associated with images, but they can and should be used on all page components including scripts, style sheets, and Flash.

Practice 4 :
Minified the Javascript/CSS
Minification removes unnecessary characters from a file to reduce its size, thereby improving load times. When a file is minified, comments and unneeded white space characters (space, newline, and tab) are removed. This improves response time since the size of the download files is reduced.

Practice 5 :
Move style sheet on top
Moving style sheets to the document HEAD element helps pages appear to load quicker since this allows pages to render progressively.

Practice 6 : 

User proximity to web servers impacts response times. Deploying content across multiple geographically dispersed servers helps users perceive that pages are loading faster.