PERF: special case numpy.dtype in is_extension_array_dtype (#39678)

Author: jorisvandenbossche

asv_bench/benchmarks/dtypes.py

@@ -2,9 +2,10 @@
 
 import numpy as np
 
+import pandas as pd
 from pandas import DataFrame
 import pandas._testing as tm
-from pandas.api.types import pandas_dtype
+from pandas.api.types import is_extension_array_dtype, pandas_dtype
 
 from .pandas_vb_common import (
     datetime_dtypes,
@@ -119,4 +120,16 @@ def time_select_dtype_string_exclude(self, dtype):
         self.df_string.select_dtypes(exclude=dtype)
 
 
+class CheckDtypes:
+    def setup(self):
+        self.ext_dtype = pd.Int64Dtype()
+        self.np_dtype = np.dtype("int64")
+
+    def time_is_extension_array_dtype_true(self):
+        is_extension_array_dtype(self.ext_dtype)
+
+    def time_is_extension_array_dtype_false(self):
+        is_extension_array_dtype(self.np_dtype)
+
+
 from .pandas_vb_common import setup  # noqa: F401 isort:skip

pandas/core/dtypes/common.py

@@ -1526,7 +1526,12 @@ def is_extension_array_dtype(arr_or_dtype) -> bool:
     False
     """
     dtype = getattr(arr_or_dtype, "dtype", arr_or_dtype)
-    return isinstance(dtype, ExtensionDtype) or registry.find(dtype) is not None
+    if isinstance(dtype, ExtensionDtype):
+        return True
+    elif isinstance(dtype, np.dtype):
+        return False
+    else:
+        return registry.find(dtype) is not None
 
 
 def is_ea_or_datetimelike_dtype(dtype: Optional[DtypeObj]) -> bool: