diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
index 87656b5c3c00..0c49c70b37fa 100644
--- a/lib/matplotlib/cbook.py
+++ b/lib/matplotlib/cbook.py
@@ -286,7 +286,7 @@ def process(self, s, *args, **kwargs):
         """
         if self._signals is not None:
             _api.check_in_list(self._signals, signal=s)
-        for cid, ref in list(self.callbacks.get(s, {}).items()):
+        for ref in list(self.callbacks.get(s, {}).values()):
             func = ref()
             if func is not None:
                 try:
@@ -1634,6 +1634,10 @@ def _safe_first_finite(obj, *, skip_nonfinite=True):
     def safe_isfinite(val):
         if val is None:
             return False
+        try:
+            return math.isfinite(val)
+        except TypeError:
+            pass
         try:
             return np.isfinite(val) if np.isscalar(val) else True
         except TypeError:
@@ -1661,7 +1665,10 @@ def safe_isfinite(val):
         raise RuntimeError("matplotlib does not "
                            "support generators as input")
     else:
-        return next((val for val in obj if safe_isfinite(val)), safe_first_element(obj))
+        for val in obj:
+            if safe_isfinite(val):
+                return val
+        return safe_first_element(obj)
 
 
 def sanitize_sequence(data):
diff --git a/lib/matplotlib/colors.py b/lib/matplotlib/colors.py
index 434bb5423543..f36e19a1d17a 100644
--- a/lib/matplotlib/colors.py
+++ b/lib/matplotlib/colors.py
@@ -210,10 +210,12 @@ def _sanitize_extrema(ex):
         ret = float(ex)
     return ret
 
+_nth_color_re = re.compile(r"\AC[0-9]+\Z")
+
 
 def _is_nth_color(c):
     """Return whether *c* can be interpreted as an item in the color cycle."""
-    return isinstance(c, str) and re.match(r"\AC[0-9]+\Z", c)
+    return isinstance(c, str) and _nth_color_re.match(c)
 
 
 def is_color_like(c):
diff --git a/lib/matplotlib/transforms.py b/lib/matplotlib/transforms.py
index f2ffa09932de..7e39807e4c71 100644
--- a/lib/matplotlib/transforms.py
+++ b/lib/matplotlib/transforms.py
@@ -189,13 +189,14 @@ def set_children(self, *children):
         # Parents are stored as weak references, so that if the
         # parents are destroyed, references from the children won't
         # keep them alive.
+        id_self = id(self)
         for child in children:
             # Use weak references so this dictionary won't keep obsolete nodes
             # alive; the callback deletes the dictionary entry. This is a
             # performance improvement over using WeakValueDictionary.
             ref = weakref.ref(
-                self, lambda _, pop=child._parents.pop, k=id(self): pop(k))
-            child._parents[id(self)] = ref
+                self, lambda _, pop=child._parents.pop, k=id_self: pop(k))
+            child._parents[id_self] = ref
 
     def frozen(self):
         """
@@ -670,6 +671,8 @@ def intersection(bbox1, bbox2):
         y1 = np.minimum(bbox1.ymax, bbox2.ymax)
         return Bbox([[x0, y0], [x1, y1]]) if x0 <= x1 and y0 <= y1 else None
 
+_default_minpos = np.array([np.inf, np.inf])
+
 
 class Bbox(BboxBase):
     """
@@ -765,7 +768,7 @@ def __init__(self, points, **kwargs):
             raise ValueError('Bbox points must be of the form '
                              '"[[x0, y0], [x1, y1]]".')
         self._points = points
-        self._minpos = np.array([np.inf, np.inf])
+        self._minpos = _default_minpos.copy()
         self._ignore = True
         # it is helpful in some contexts to know if the bbox is a
         # default or has been mutated; we store the orig points to
@@ -1773,7 +1776,7 @@ def __array__(self, *args, **kwargs):
 
     def __eq__(self, other):
         if getattr(other, "is_affine", False) and hasattr(other, "get_matrix"):
-            return np.all(self.get_matrix() == other.get_matrix())
+            return (self.get_matrix() == other.get_matrix()).all()
         return NotImplemented
 
     def transform(self, values):