Optimizations to reduce website loading time

Question

What are some important optimizations that can be made to a website to reduce the loading time?

Answer 1

install firebug and pagespeed plugin follows all the pagespeed directives (until possible) and be happy http://code.google.com/intl/it/speed/page-speed/

anyway the most importante optimization in my experience is to reduce the number of HTTP requests to a minimum...