Samurais had something called bushido, way of the warrior, code of conduct they had to follow. In similar manner you have to follow certain opt-dō if you want to optimize your application. I have tried to sketch such a path in my nodecamp.eu talk “Understanding V8” and +Daniel Clifford tried to do the same in “V8 Performance Tuning Tricks” talk on GDD11 in Berlin. But not everybody has seen those talks and the question keeps coming back again. So I decided to write down a quick check list for developers who want to optimize their apps. tl;dr version of my checklist is: “Understand before you act”.