The ICMA Center for Performance Measurement would most likely be what you're looking for: http://icma.org/en/results/center_for_performance_measurement/home
CPM regularly does work on performance benchmarks, and puts out regular publications. Your best bet would probably be the annual data reports, which compile and compare performance measurement data from over 40 different cities and towns throughout the country on many different subjects. CPM also publishes "What Works", which offers dozens of real-world examples of cities utilizing successful performance measurement strategies.
Also, the Knowledge Network has an entire "Performance Measurement" topic page that compiles documents, articles and a history of questions asked by members. All are valuable resources to help get you started.