The read-back check (fallback to unmerged pieces) imported every export. Now it runs only when some body actually had faces merged. Oracle 41 (42 faces, nothing merged): export no longer re-imports, which saved 7 s. Pipe flange (merges): 1.1 s for the read-back. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL