hashfile/checkout: use save_many to save state

For MNIST dataset, this drops total runtime for `dvc add` from 24s
to 12s for me.

src/dvc_data/hashfile/checkout.py

@@ -13,6 +13,7 @@
     from fsspec import Callback
 
     from ._ignore import Ignore
+    from .hash_info import HashInfo
 
 logger = logging.getLogger(__name__)
 
@@ -110,10 +111,6 @@ def _checkout_file(
     else:
         link(cache, cache_path, fs, path)
         modified = True
-
-    if state:
-        state.save(path, fs, change.new.oid)
-
     return modified
 
 
@@ -203,6 +200,7 @@ def _checkout(
         _remove(entry_path, fs, change.old.in_cache, force=force, prompt=prompt)
 
     failed = []
+    hashes_to_update: list[tuple[str, HashInfo, None]] = []
     for change in chain(diff.added, diff.modified):
         entry_path = fs.join(path, *change.new.key) if change.new.key != ROOT else path
         if change.new.oid.isdir:
@@ -223,6 +221,11 @@ def _checkout(
             )
         except CheckoutError as exc:
             failed.extend(exc.paths)
+        else:
+            hashes_to_update.append((entry_path, change.new.oid, fs.info(entry_path)))
+
+    if state is not None:
+        state.save_many(hashes_to_update, fs)
 
     if failed:
         raise CheckoutError(failed)