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ParparVM’s HashMap suffered catastrophic miss latency due to linear probing on dense integer keys. By adopting CPython‑style perturbed probing (Swiss‑table style) and extending tagged immediate values to more primitives, miss latency dropped from 32 s to ~45 ms, allocation pressure fell dramatically, and overall performance stayed roughly flat despite a modest hit‑time slowdown.
The post explains that Python’s `in` operator first looks for a `__contains__` method on the object and uses its boolean result; if absent it falls back to iterating via `__iter__`. Implementing `__contains__` can make membership checks faster, especially for large collections, by avoiding full iteration.
This is an interactive quiz testing understanding of Python 3.15's new `frozendict` type. It covers how to build a frozen mapping, its hashability, and why it isn't a `dict` subclass.
