diff --git a/aiter/jit/core.py b/aiter/jit/core.py
index 098af6ce6a..68c09aeb73 100644
--- a/aiter/jit/core.py
+++ b/aiter/jit/core.py
@@ -190,7 +190,7 @@ def update_config_files(self, file_path: str, merge_name: str):
 
         for i, path in enumerate(path_list):
             if not os.path.exists(path):
-                logger.info(f"path {i+1}: {path} (not exist)")
+                logger.info(f"path {i + 1}: {path} (not exist)")
                 continue
 
             df = pd.read_csv(path)
@@ -916,7 +916,7 @@ def exec_blob(blob_gen_cmd, op_dir, src_dir, sources):
 
     def FinalFunc():
         logger.info(
-            f"\033[32mfinish build [{md_name}], cost {time.perf_counter()-startTS:.1f}s \033[0m"
+            f"\033[32mfinish build [{md_name}], cost {time.perf_counter() - startTS:.1f}s \033[0m"
         )
 
     mp_lock(lockPath=lock_path, MainFunc=MainFunc, FinalFunc=FinalFunc)
@@ -1130,6 +1130,8 @@ def _ctypes_call(func, fc_name, md_name):
 
     _cache = {}
     _arg_checked = False
+    _sig = inspect.signature(func)
+    _hints = typing.get_type_hints(func)
 
     def _ensure_loaded():
         if _cache:
@@ -1168,8 +1170,7 @@ def _opt_sym(name, argtypes=(), restype=None):
         err_getter = _opt_sym("aiter_get_last_error", restype=ctypes.c_char_p)
         err_clear = _opt_sym("aiter_clear_last_error")
 
-        hints = typing.get_type_hints(func)
-        ret_hint = hints.get("return")
+        ret_hint = _hints.get("return")
         ctypes_data_return = ctypes_status_mode and ret_hint is int
 
         if ctypes_status_mode:
@@ -1183,8 +1184,8 @@ def _opt_sym(name, argtypes=(), restype=None):
 
         argtypes = []
         has_tensor = False
-        for pname in inspect.signature(func).parameters:
-            hint = hints.get(pname)
+        for pname in _sig.parameters:
+            hint = _hints.get(pname)
             origin = typing.get_origin(hint)
             type_args = typing.get_args(hint)
             if hint is torch.Tensor:
@@ -1252,20 +1253,17 @@ def _check_args_before_convert(bound_args, hints):
             elif hint is str:
                 if not isinstance(value, str):
                     raise TypeError(
-                        f"{fc_name}: '{pname}' expects str, "
-                        f"got {type(value).__name__}"
+                        f"{fc_name}: '{pname}' expects str, got {type(value).__name__}"
                     )
             elif hint is bool:
                 if not isinstance(value, (bool, int)):
                     raise TypeError(
-                        f"{fc_name}: '{pname}' expects bool, "
-                        f"got {type(value).__name__}"
+                        f"{fc_name}: '{pname}' expects bool, got {type(value).__name__}"
                     )
             elif hint is int:
                 if not isinstance(value, int):
                     raise TypeError(
-                        f"{fc_name}: '{pname}' expects int, "
-                        f"got {type(value).__name__}"
+                        f"{fc_name}: '{pname}' expects int, got {type(value).__name__}"
                     )
             elif hint is float:
                 if not isinstance(value, (float, int)):
@@ -1287,13 +1285,11 @@ def caller(*args, **kwargs):
             from ..test_common import log_args
 
             log_args(func, *args, **kwargs)
-        sig = inspect.signature(func)
-        bound = sig.bind(*args, **kwargs)
+        bound = _sig.bind(*args, **kwargs)
         bound.apply_defaults()
-        hints = typing.get_type_hints(func)
 
         if not _arg_checked:
-            _check_args_before_convert(bound.arguments, hints)
+            _check_args_before_convert(bound.arguments, _hints)
             _arg_checked = True
 
         c_args = []
@@ -1301,7 +1297,7 @@ def caller(*args, **kwargs):
         tensor_device = None
 
         for pname, value in bound.arguments.items():
-            hint = hints.get(pname)
+            hint = _hints.get(pname)
             origin = typing.get_origin(hint)
             type_args = typing.get_args(hint)