diff --git a/arborist/cli.py b/arborist/cli.py
index 03df400..13a36b9 100644
--- a/arborist/cli.py
+++ b/arborist/cli.py
@@ -2995,10 +2995,29 @@ def _cmd_cold_unpack(args: argparse.Namespace) -> int:
     # directory; --hydrate-M picks the routing modulus. Each incoming
     # row lands on shard_for_document(root, M).
     if args.hydrate_shards_dir:
+        import sqlite3
         target_dir = Path(args.hydrate_shards_dir).expanduser()
         target_dir.mkdir(parents=True, exist_ok=True)
         M = args.hydrate_M
         target_paths = [target_dir / f"{i:03d}.db" for i in range(M)]
+
+        # #000067 bench-max: bump page_size before schema applies so the
+        # corpus uses 16 KB pages instead of SQLite's 4 KB default.
+        # Bigger pages → ~4× fewer page writes during chunk-fill →
+        # ~4× fewer ext4 metadata journal events (jbd2_log_wait_commit
+        # was the measured bottleneck on the 3090). page_size CAN ONLY
+        # be set on an empty DB; VACUUM finalises it. Idempotent on
+        # re-runs since fresh hydrate dirs are clean.
+        for p in target_paths:
+            if not p.exists() or p.stat().st_size == 0:
+                pre = sqlite3.connect(str(p))
+                try:
+                    pre.execute("PRAGMA page_size = 16384")
+                    pre.execute("PRAGMA secure_delete = OFF")
+                    pre.execute("VACUUM")  # commit the page_size change
+                finally:
+                    pre.close()
+
         targets: list = []
         for p in target_paths:
             t = connect(p)