How to speed up the php website?

There some list of url to speed up the website.

1) Optimize site speed:

http://www.improvetheweb.com/how-to-optimize-site-speed

2) The basic rules speedup your website:

http://www.webmaster-talk.com/website-design-forum/44591-basic-ways-speed-up-your-website.html

3) Using memcache to increase speed up website:

http://www.host.co.in/forums/f28/how-increase-website-speed-using-memcache-938/

4) There is a blog to speed up website and increase conversions :

http://www.modernblue.com/web-design-blog/speed-up-your-website-and-increase-conversions/

5) Make the website faster :
http://groups.google.com/group/make-the-web-faster/browse_thread/thread/ddfbe82dd80408cc

6) To compare the php language website with other languages:

http://www.procata.com/blog/archives/2006/02/09/comparing-php-with-other-languages

Thank you.