Measured (10M entities through the real chunk source, both monomorphic and
16-subclass polymorphic populations): a bare `foreach { PushToCache(entity); }`
runs at 2.3ns/entity while the same loop carrying the heavy-entity check
(interface SerializedLength read + branch) runs at 5.3-5.7ns - 2.3x slower.
Type diversity barely matters; the cost is the fatter loop body, confirming
that per-entity logic in the push loop defeats the JIT's tight-loop codegen.
Entities over 1MB are rare in practice - realistically only whole
GenericPersistence self-payloads, which are already published as dedicated
single chunks - so the fallback loop drops the check and rare thick entities
ride inside shared chunks (bounded tail, same behavior as the slot-range fast
path). The now-unused HeavyEntityThreshold constant is removed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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