How do I write fast Node.js code with V8 in mind?
Profile first to find the real bottleneck, keep hot functions monomorphic (consistent argument types), initialize objects fully (avoid hidden class changes), avoid delete and with, keep arrays homogeneous, and prefer rest parameters over arguments in hot code.
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More FAQs in V8 Performance Tips for Node.js Developers
Because premature optimization based on guesses wastes time. Use the Node.js inspector and CPU profiler to find what is actually slow, then optimize the real bottleneck. Measure first, always.
Because delete changes an object's hidden class, which deoptimizes the code in V8. Set properties to undefined instead, or restructure the object differently, to keep the hidden class stable and V8 optimizations intact.
Because mixed-type arrays (numbers and objects mixed) prevent V8 from optimizing array operations. Keep arrays of the same type in hot code, and pre-allocate to a known size to avoid reallocation overhead.
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