The EAGLE bigram fallback built 64K-token keys with an index-based
Python comprehension (6.3 ms per call at 64K tokens). zip + islice
runs the pairing loop in C and avoids copying the shifted operand:
3.6-4.2 ms per call (~1.6x). Output is byte-identical (same tuples);
the tai-kernel fast path is unaffected.
Packing bigrams into int64s via numpy was measured and rejected: the
list<->array boxing makes it slower (4.1 ms) than zip until token ids
are numpy end-to-end, and it would change HiCache storage hash inputs.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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