Hi Friends,
I have Used Few of Tricks at the time of Drupal Website Development and that Tricks finally works. So below i am mentioning tips that really useful for you.
1. Use YSlow
2. Use tools.pingdom.com to see if there is anything obviously slow
3. Compress js and css using YUI compressor
4. Only use cookies where necessary
5. Use APC/Xcache
6. Tune PHP params
7. Use separate server for static. Use nginx
8. Use varnish to cache