Optimize IntoIter::nth on v1 - #6
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Summary
Implement
IntoIter::nthby advancing past the skipped prefix once and dropping that prefix as a slice. This avoids visiting each skipped element when the type has no destructor, while still cleaning up the skipped range if a destructor panics.Across five native Rust benchmark pairs on x86_64 Linux,
nthtook 16–17% less time at the inline-capacity boundary and 63–66% less for 4,096u64elements. Small inline cases were roughly unchanged. Some unchanged controls were sensitive to binary layout, so these results support the boundary and spilled cases rather than a general iterator speedup.The added native benchmarks were removed in a follow-up commit and remain in the PR history.