debugFullConsistencyChecks property
Opt-in: run the FULL cross-structure consistency sweep (whole order walk, nid-table walks, every animation mirror) after every incremental order mutation in debug builds. Off by default, the sweep makes N sequential inserts O(N^2) in debug; the default is an O(changed-range) order/reverse-index agreement check. The fuzz/purge suites, which exist to exercise the invariants, enable this.
Implementation
static bool debugFullConsistencyChecks = false;