Here’s a great article about performance tuning web applications. In short, have a goal, and measure, measure, measure. Otherwise, you’re just shooting in the dark at a pin in a haystack. Or something like that.
I’ve touched on the complexity of performance testing web applications before, but this article goes me one better by outlining various tools that can be used to actual test different pieces of the stack.
I did notice one missing piece, though. The SitePen folks outline tools to test from the browser to the web server, and then the database server. But they don’t mention any app server or web server profilers. I wonder whether that’s an unintentional oversight, or whether they haven’t needed to tune dynamic business logic, either in the app server or web server layer.
I don’t have any business logic layer performance tuning tools to suggest, either. Looks like sourceforge.net has a number of profilers–anyone have experience using one?