Good post about enhancing the performance of your website. To sum up, here are the 25 things you should concentrate.

1. Minimize HTTP request
2. Use a CDN - Content Delivery Network
3. Add an Expieres / Cache-Control header
4. Compress the Contents
5. Stylesheets on top
6. Use scripts at the bottom ( Seriously solves many issues )
7. No CSS Expressions
8. No Inline Javascript / CSS
9. Reduce DNS Lookups
10. Avoid Redirects
11. Remove Duplicate Scripts
12. Configure ETags
13. Make Ajax Cacheable
14. Flush the Buffer Early
15. Use GET requests for Ajax
16. Pre/Post load components
17. Make DOM Light weight
18. Minimize IFrame or No IFrames
19. No 404s ( yes, make 404 user friendly )
20. Reduce Cookie Size
21. Smart Event Handler ( needs real smart programmers )
22. No @import statements
23. No filters for images
24. Try to cache most of the resources ( favicon, css, js )
25. Anything should be < 25k ( better is one page download is < 25K)

Warning: The blog post you are going to read is really big.