From 36cb4b0c671e52d0a89dd904338391be0cb118ee Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Fri, 7 Jun 2024 11:19:38 -0700
Subject: [PATCH 1/2] PERF: Only copy in plotting when needed

---
 pandas/plotting/_core.py                  | 11 +++++------
 pandas/tests/plotting/frame/test_frame.py |  2 +-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/pandas/plotting/_core.py b/pandas/plotting/_core.py
index 0daf3cfafe81c..097d45a7eb756 100644
--- a/pandas/plotting/_core.py
+++ b/pandas/plotting/_core.py
@@ -982,10 +982,7 @@ def __call__(self, *args, **kwargs):
                 f"Valid plot kinds: {self._all_kinds}"
             )
 
-        # The original data structured can be transformed before passed to the
-        # backend. For example, for DataFrame is common to set the index as the
-        # `x` parameter, and return a Series with the parameter `y` as values.
-        data = self._parent.copy()
+        data = self._parent
 
         if isinstance(data, ABCSeries):
             kwargs["reuse_plot"] = True
@@ -1032,8 +1029,10 @@ def __call__(self, *args, **kwargs):
                         except (IndexError, KeyError, TypeError):
                             pass
 
-                # don't overwrite
-                data = data[y].copy()
+                data = data[y]
+                if x is None:
+                    # don't overwrite
+                    data = data.copy()
 
                 if isinstance(data, ABCSeries):
                     label_name = label_kw or y
diff --git a/pandas/tests/plotting/frame/test_frame.py b/pandas/tests/plotting/frame/test_frame.py
index e809bd33610f1..b381c4fce8430 100644
--- a/pandas/tests/plotting/frame/test_frame.py
+++ b/pandas/tests/plotting/frame/test_frame.py
@@ -1120,7 +1120,7 @@ def test_boxplot_return_type_invalid_type(self, return_type):
 
     def test_kde_df(self):
         pytest.importorskip("scipy")
-        df = DataFrame(np.random.default_rng(2).standard_normal((100, 4)))
+        df = DataFrame(np.random.default_rng(2).standard_normal((10, 4)))
         ax = _check_plot_works(df.plot, kind="kde")
         expected = [pprint_thing(c) for c in df.columns]
         _check_legend_labels(ax, labels=expected)

From 6f2724e183ef655e10e687afe67061faa2438c3e Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Fri, 7 Jun 2024 11:39:35 -0700
Subject: [PATCH 2/2] Remove more unnecessary copies

---
 pandas/plotting/_core.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/pandas/plotting/_core.py b/pandas/plotting/_core.py
index 097d45a7eb756..0a29ab530c2fc 100644
--- a/pandas/plotting/_core.py
+++ b/pandas/plotting/_core.py
@@ -1002,7 +1002,7 @@ def __call__(self, *args, **kwargs):
                     if is_integer(y) and not holds_integer(data.columns):
                         y = data.columns[y]
                     # converted to series actually. copy to not modify
-                    data = data[y].copy()
+                    data = data[y].copy(deep=False)
                     data.index.name = y
         elif isinstance(data, ABCDataFrame):
             data_cols = data.columns
@@ -1030,9 +1030,6 @@ def __call__(self, *args, **kwargs):
                             pass
 
                 data = data[y]
-                if x is None:
-                    # don't overwrite
-                    data = data.copy()
 
                 if isinstance(data, ABCSeries):
                     label_name = label_kw or y