Performance Tuning Best Practices

• Code the use case you want to profile pointing to raw build files.
• Run the code through Chrome profiler, which gives you:
  • stack traces without anonymous functions
  • memory
  • CPU
  • CSS
  • best initial tool to identify bottlenecks
• Run the code through Firefox profiler, which additionally gives you function call counts.
• Once you've identified bottlenecks you want to address:
  • define hypotheses on how to eliminate those bottlenecks
  • write a range of tests that address micro and macro level use cases for the function(s) in question
  • benchmark potential fixes against multiple target environments
• Focus on algorithmic changes more than micro-optimizations.
• Focus on DOM more than JS.
• Don't make any assumptions.
• Be very data driven.
• Understand how the different JS engines work.
• Tests get checked into src/[module]/tests/perf.