python
@@ -576,7 +576,7 @@ def read_bytes(self):
         """
         Open the file in bytes mode, read it, and close the file.
         """
-        with self.open(mode='rb') as f:
+        with self.open(mode='rb', buffering=0) as f:
             return f.read()
 
     def read_text(self, encoding=None, errors=None, newline=None):

@@ -1465,7 +1465,7 @@ def stat(self, *, follow_symlinks=True):
 
     def open(self, mode='r', buffering=-1, encoding=None,
              errors=None, newline=None):
-        if buffering != -1:
+        if buffering != -1 and not (buffering == 0 and 'b' in mode):
             raise NotImplementedError
         path_obj = self.resolve()
         path = str(path_obj)

diff --git a/Misc/NEWS.d/next/Library/2024-07-22-08-57-28.gh-issue-120754.Eo5puP.rst b/Misc/NEWS.d/next/Library/2024-07-22-08-57-28.gh-issue-120754.Eo5puP.rst
@@ -0,0 +1 @@
+``Pathlib.read_bytes`` no longer opens the file in Python's buffered I/O mode. This reduces overheads as the code reads a file in whole leading to a modest speedup.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		``Pathlib.read_bytes`` no longer opens the file in Python's buffered I/O mode. This reduces overheads as the code reads a file in whole leading to a modest speedup.