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.
Defining the coordinates of image maps can be tedious and error prone.
Using image maps for navigation is not accessible too, so it's not recommended.
Inline images use the URL scheme to embed the image data in the actual page. Combining inline images into your (cached) stylesheets is a way to reduce HTTP requests and avoid increasing the size of your pages.
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.
Image maps only work if the images are contiguous in the page, such as a navigation bar.