How to improve the performance of your web application.

STOP.    Look in the mirror.   Proceed.

If you are a web developer, the first thing that you need to know about performance tuning is that you have more power than you think.   This is not so much a tutorial for you as an eye opening event.  Sure you can throw more memory, more CPU power, or more disk space at the problem.  And certainly, that will help.   But the #1 rule that you should know is that it is unlikely that your code is already as streamlined as can be.  You may need to index your database tables, or perhaps enable application caching, or maybe your SQL queries are performing inefficient joins.   Whatever the case, look at your code before making your employer take money from someone else’s paycheck to pay for that new SAN and that excessive amount of RAM for you.