perf(interopDefault): add caching to reduce Proxy overhead by ~2x#421
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The interopDefault Proxy wrapper was causing significant performance overhead (60-70x slower than native) due to: - Reflect.has() called on every property access - Reflect.get() called on every property access - .bind() called on every access for functions from default export This adds a Map-based cache that stores property values after first access, eliminating repeated lookups. Results: - Named exports: 66x -> 39x slower (~2x improvement) - Fallback to default: 38x -> 24x slower (~1.6x improvement) The remaining overhead is inherent to JavaScript Proxies and cannot be eliminated while maintaining the same behavior. Also adds a warning to README.md about the performance cost of interopDefault and recommends disabling it for hot paths. Closes unjs#420
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Summary
interopDefaultProxy to reduce repeated lookupstest/bench-interop.mjs)Problem
The
interopDefaultProxy wrapper was causing significant performance overhead (60-70x slower than native) due to:Reflect.has()called on every property accessReflect.get()called on every property access.bind()called on every access for functions from default exportSolution
Added a
Map-based cache that stores property values after first access, eliminating repeated lookups.Results:
The remaining overhead is inherent to JavaScript Proxies and cannot be eliminated while maintaining the same behavior.
Test plan
Closes #420