diff --git a/renderers/base.py b/renderers/base.py
index a8823fe..170e31d 100644
--- a/renderers/base.py
+++ b/renderers/base.py
@@ -663,8 +663,13 @@ def load_tokenizer(model_name_or_path: str):
             model_name_or_path,
             trust_remote_code=True,
             revision=revision,
+            use_fast=True,
         )
-    return AutoTokenizer.from_pretrained(model_name_or_path, trust_remote_code=False)
+    return AutoTokenizer.from_pretrained(
+        model_name_or_path,
+        trust_remote_code=False,
+        use_fast=True,
+    )
 
 
 def _populate_registry():
diff --git a/tests/test_load_tokenizer.py b/tests/test_load_tokenizer.py
index 5445687..f40ee1b 100644
--- a/tests/test_load_tokenizer.py
+++ b/tests/test_load_tokenizer.py
@@ -50,11 +50,11 @@ def test_trusted_revisions_are_full_shas():
 
 @patch("transformers.AutoTokenizer.from_pretrained")
 def test_unlisted_model_loads_without_remote_code(mock_from_pretrained):
-    """Default path: trust_remote_code=False, no revision pin."""
+    """Default path: trust_remote_code=False, use_fast=True, no revision pin."""
     load_tokenizer("Qwen/Qwen3-0.6B")
     args, kwargs = mock_from_pretrained.call_args
     assert args == ("Qwen/Qwen3-0.6B",)
-    assert kwargs == {"trust_remote_code": False}
+    assert kwargs == {"trust_remote_code": False, "use_fast": True}
 
 
 @patch("transformers.AutoTokenizer.from_pretrained")
@@ -67,6 +67,7 @@ def test_kimi_loads_with_pinned_revision(mock_from_pretrained):
     assert kwargs == {
         "trust_remote_code": True,
         "revision": TRUSTED_REVISIONS["moonshotai/Kimi-K2.5"],
+        "use_fast": True,
     }
 
 
@@ -87,8 +88,9 @@ def test_unknown_path_falls_through_to_no_remote_code(mock_from_pretrained):
         load_tokenizer(name)
         args, kwargs = mock_from_pretrained.call_args
         assert args == (name,)
-        assert kwargs == {"trust_remote_code": False}, (
-            f"{name}: unlisted path leaked trust_remote_code=True"
+        assert kwargs == {"trust_remote_code": False, "use_fast": True}, (
+            f"{name}: unlisted path leaked trust_remote_code=True "
+            f"or dropped use_fast=True"
         )