Minor readability improvements.  Also note performance impact of __slots__. (GH-24456)

diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index 5455d91..94a8b4e 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -42,8 +42,8 @@
 Simple example: A descriptor that returns a constant
 ----------------------------------------------------
 
-The :class:`Ten` class is a descriptor that always returns the constant ``10``
-from its :meth:`__get__` method:
+The :class:`Ten` class is a descriptor whose :meth:`__get__` method always
+returns the constant ``10``:
 
 .. testcode::
 
@@ -70,10 +70,10 @@
     >>> a.y                         # Descriptor lookup
     10
 
-In the ``a.x`` attribute lookup, the dot operator finds the key ``x`` and the
-value ``5`` in the class dictionary.  In the ``a.y`` lookup, the dot operator
-finds a descriptor instance, recognized by its ``__get__`` method, and calls
-that method which returns ``10``.
+In the ``a.x`` attribute lookup, the dot operator finds ``'x': 5``
+in the class dictionary.  In the ``a.y`` lookup, the dot operator
+finds a descriptor instance, recognized by its ``__get__`` method.
+Calling that method returns ``10``.
 
 Note that the value ``10`` is not stored in either the class dictionary or the
 instance dictionary.  Instead, the value ``10`` is computed on demand.
@@ -300,7 +300,7 @@
 created or the name of class variable it was assigned to.  (This method, if
 present, is called even if the class is not a descriptor.)
 
-Descriptors get invoked by the dot "operator" during attribute lookup.  If a
+Descriptors get invoked by the dot operator during attribute lookup.  If a
 descriptor is accessed indirectly with ``vars(some_class)[descriptor_name]``,
 the descriptor instance is returned without invoking it.
 
@@ -1380,7 +1380,10 @@
 design pattern <https://en.wikipedia.org/wiki/Flyweight_pattern>`_ likely only
 matters when a large number of instances are going to be created.
 
-4. Blocks tools like :func:`functools.cached_property` which require an
+4. Improves speed.  Reading instance variables is 35% faster with
+``__slots__`` (as measured with Python 3.10 on an Apple M1 processor).
+
+5. Blocks tools like :func:`functools.cached_property` which require an
 instance dictionary to function correctly:
 
 .. testcode::