cornwallis

Here's a few things:
 
1. Use a decent web host
- many cheap hosts oversell their servers which can slow down response times
 
2. Reduce http requests
- use image assets sparingly, if your design is image heavy that will add to http requests
- use content images sparingly, only use what the visitor really needs
- use an icon font instead of image based icons
- don't use multiple stylesheets, if you have more than one combine them into a single document
 
3. Javascript
- if you use javascript libraries and plugins always use the minified versions, then also minify/combine into one download as well
- only call JS + plugins on pages you actually need them
- consider using hosted libraries whenever possible as it's likely your visitors will already have them cached
 
4. CSS
- reuse styles where you can to keep the file size down
- minify CSS
 
5. HTML
- write clean code to keep document size down, all those DIV's can add up and increase documents size and render time
 
6. Images
- optimise!
- use the correct format, eg .jpg for photo based images, .png for others

There are several things you can do, some of the most common ones are:
- Minify CSS/JS (only for your live enviroment, keep a clean version for development as a minifyed source code is hard to work with)
- Try to put all CSS/JS in as few files as possable
- You can use an image sprite for all your template images so it only sends one http request and not several (an example: http://en.wikipedia.org/wiki/File:Sprite-example.gif)
- optimize images