In the perspective of content......

• Minimize HTTP requests, such as CSS sprite, inline image, and files combination.
• Minimize DOM elements.

In the aspect of server and Cookie......

• Utilize CDN, config ETag, and compress components using Gzip.
• Reduce the size of cookie

In terms of CSS......

• Avoid CSS expressions
• Put the stylesheet on top of the file
• Using <link> but not @import

Ok...What can we do on Javascript......

• Put Javascript on the bottom of the HTML file
• Import JS file from outside
• Minimize DOM operation
• A lot more we can do on Javascript, but that will be another HUGE topic then.