Opening an xref-heavy drawing froze for ~22s before the first frame.
`synced_hatch_models` walked every INSERT and called
`explode_from_document()` to scan the result for hatch fills — but explode
CLONES every child of the block, including 3D solids that each carry tens
of KB of SAB geometry. Clinic.dwg's five xref INSERTs each reference a
discipline block of thousands of solids and no hatch, so this materialized
~25000 solid clones (~1 GB) on every open just to find zero hatches.
Add a memoized `block_contains_hatch`: a read-only scan of the block's
entity types (recursing nested INSERTs, cycle-guarded) that skips the
explode for blocks containing no hatch, transitively. Blocks that do hold
a hatch still explode exactly as before, so the hatch set is unchanged.
Hatch build for Clinic.dwg drops from ~21.7s to ~0.02s, cutting the total
open-to-first-frame time from ~25s to ~5s.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
0ce918da68