Optimization killers in Node.js

This  link will contain advice to avoid writing code that will perform significantly worse than expected. Specifically those patterns that cause V8 (relevant to Node.JS, Opera, Chromium...) to refuse to optimize the affected function.

Some V8 background

In V8 there is no interpreter but there are 2 different compilers: generic and optimizing. That means your Javascript is always compiled and run directly as native code. That means it's fast, right? Wrong. Code being compiled to native code by itself isn't hugely significant for performance. It just removes interpreter overhead but the code will still be slow if not optimized.

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