Reducing the number of HTTP requests in your page is the place to start.
This is the most important guideline for improving performance for first time visitors.
As described in Tenni Theurer's blog post Browser Cache Usage - Exposed!
tag: content 80% of the end-user response time is spent on the front-end.
Most of this time is tied up in downloading all the components in the page: images, stylesheets, scripts, Flash, etc.
Reducing the number of components in turn reduces the number of HTTP requests required to render the page. One way to reduce the number of components in the page is to simplify the page's design.
But is there a way to build pages with richer content while also achieving fast response times?
Here are some techniques for reducing the number of HTTP requests, while still supporting rich page designs.
Combined files are a way to reduce the number of HTTP requests by combining all scripts into a single script, and similarly combining all CSS into a single stylesheet.
Combining files is more challenging when the scripts and stylesheets vary from page to page, but making this part of your release process improves response times.
CSS Sprites are the preferred method for reducing the number of image requests.
Combine your background images into a single image and use the CSS properties to display the desired image segment.
Image maps combine multiple images into a single image.
The overall size is about the same, but reducing the number of HTTP requests speeds up the page.