I came across this post earlier this year, showing how various plugins affect the performance of a wordpress install, by using a tracker class to measure how long each plugin takes to execute each time a page is loaded:
http://www.dev4press.com/2011/blog/benchmark/measuring-impact-of-plugins-on-wordpress-loading
In that article, they did it using part of plugin that’s available as part of paid bundle from GD Press.
Are there other alternative plugins that also let you find the bottlenecks in your own code, in production, without resorting to using NewRelic, or something complex, like running webgrind or an equivalent for local development?
There’s a free to download ‘lite’ version of the GDPress Tools plugin that may sort you out, but it’s probably preferable and more accurate to use XDebug + KCachegrind.
FWIW, the latest build of PHPStorm integrates with XDebug’s profiler to handle the data presentation and visualisation side.