Caching is a great way of improving the performance of your web sites. In ASP.NET, simply add
<%@ OutputCache Duration="60" VaryByParam="*" %>
Where Duration is the number of seconds you wish to have the resulting page stored in memory.
If you forget about caching and end up wondering why sometimes you hit your breakpoint, but not other times and end up yelling some expletives that your children ask what they mean, well then caching isn't all that.