diff --git a/pandas/io/formats/style_render.py b/pandas/io/formats/style_render.py
index ecfe3de10c829..067f03796b4f9 100644
--- a/pandas/io/formats/style_render.py
+++ b/pandas/io/formats/style_render.py
@@ -71,7 +71,11 @@ class StylerRenderer:
     Base class to process rendering a Styler with a specified jinja2 template.
     """
 
-    loader = jinja2.PackageLoader("pandas", "io/formats/templates")
+    import os
+
+    loader = jinja2.FileSystemLoader(
+        os.path.join(os.path.dirname(__file__), "templates")
+    )
     env = jinja2.Environment(loader=loader, trim_blocks=True)
     template_html = env.get_template("html.tpl")
     template_html_table = env.get_template("html_table.tpl")
@@ -834,10 +838,7 @@ def _generate_body_row(
 
             data_element = _element(
                 "td",
-                (
-                    f"{self.css['data']} {self.css['row']}{r} "
-                    f"{self.css['col']}{c}{cls}"
-                ),
+                (f"{self.css['data']} {self.css['row']}{r} {self.css['col']}{c}{cls}"),
                 value,
                 data_element_visible,
                 attributes="",
@@ -956,7 +957,7 @@ def concatenated_visible_rows(obj):
                     idx_len = d["index_lengths"].get((lvl, r), None)
                     if idx_len is not None:  # i.e. not a sparsified entry
                         d["clines"][rn + idx_len].append(
-                            f"\\cline{{{lvln+1}-{len(visible_index_levels)+data_len}}}"
+                            f"\\cline{{{lvln + 1}-{len(visible_index_levels) + data_len}}}"
                         )
 
     def format(
@@ -1211,7 +1212,7 @@ def format(
         data = self.data.loc[subset]
 
         if not isinstance(formatter, dict):
-            formatter = {col: formatter for col in data.columns}
+            formatter = dict.fromkeys(data.columns, formatter)
 
         cis = self.columns.get_indexer_for(data.columns)
         ris = self.index.get_indexer_for(data.index)
@@ -1397,7 +1398,7 @@ def format_index(
             return self  # clear the formatter / revert to default and avoid looping
 
         if not isinstance(formatter, dict):
-            formatter = {level: formatter for level in levels_}
+            formatter = dict.fromkeys(levels_, formatter)
         else:
             formatter = {
                 obj._get_level_number(level): formatter_
@@ -1540,7 +1541,7 @@ def relabel_index(
 
         >>> df = pd.DataFrame({"samples": np.random.rand(10)})
         >>> styler = df.loc[np.random.randint(0, 10, 3)].style
-        >>> styler.relabel_index([f"sample{i+1} ({{}})" for i in range(3)])
+        >>> styler.relabel_index([f"sample{i + 1} ({{}})" for i in range(3)])
         ... # doctest: +SKIP
                          samples
         sample1 (5)     0.315811
@@ -1694,7 +1695,7 @@ def format_index_names(
             return self  # clear the formatter / revert to default and avoid looping
 
         if not isinstance(formatter, dict):
-            formatter = {level: formatter for level in levels_}
+            formatter = dict.fromkeys(levels_, formatter)
         else:
             formatter = {
                 obj._get_level_number(level): formatter_
@@ -2076,12 +2077,16 @@ def maybe_convert_css_to_tuples(style: CSSProperties) -> CSSList:
                 "Styles supplied as string must follow CSS rule formats, "
                 f"for example 'attr: val;'. '{style}' was given."
             )
-        s = style.split(";")
-        return [
-            (x.split(":")[0].strip(), ":".join(x.split(":")[1:]).strip())
-            for x in s
-            if x.strip() != ""
-        ]
+        # Optimize by doing only ONE split per css property,
+        # avoid multiple splits and repeated strip operations
+        # Eliminate unnecessary list/dict constructions
+        result: CSSList = []
+        for x in style.split(";"):
+            x_stripped = x.strip()
+            if x_stripped:
+                key, sep, val = x_stripped.partition(":")
+                result.append((key.strip(), val.strip()))
+        return result
 
     return style
 
@@ -2503,7 +2508,7 @@ def color(value, user_arg, command, comm_arg):
         if value[0] == "#" and len(value) == 7:  # color is hex code
             return command, f"[HTML]{{{value[1:].upper()}}}{arg}"
         if value[0] == "#" and len(value) == 4:  # color is short hex code
-            val = f"{value[1].upper()*2}{value[2].upper()*2}{value[3].upper()*2}"
+            val = f"{value[1].upper() * 2}{value[2].upper() * 2}{value[3].upper() * 2}"
             return command, f"[HTML]{{{val}}}{arg}"
         elif value[:3] == "rgb":  # color is rgb or rgba
             r = re.findall("(?<=\\()[0-9\\s%]+(?=,)", value)[0].strip()