diff --git a/src/flake8/checker.py b/src/flake8/checker.py
index 18b1ff6..522d650 100644
--- a/src/flake8/checker.py
+++ b/src/flake8/checker.py
@@ -4,7 +4,6 @@ from __future__ import annotations
 import argparse
 import collections
 import errno
-import itertools
 import logging
 import multiprocessing.pool
 import signal
@@ -80,9 +79,7 @@ class Manager:
             "physical lines": 0,
             "tokens": 0,
         }
-        self.exclude = tuple(
-            itertools.chain(self.options.exclude, self.options.extend_exclude)
-        )
+        self.exclude = (*self.options.exclude, *self.options.extend_exclude)
 
     def _process_statistics(self) -> None:
         for checker in self.checkers:
diff --git a/src/flake8/style_guide.py b/src/flake8/style_guide.py
index 94698f8..8431650 100644
--- a/src/flake8/style_guide.py
+++ b/src/flake8/style_guide.py
@@ -6,7 +6,6 @@ import contextlib
 import copy
 import enum
 import functools
-import itertools
 import logging
 from typing import Generator
 from typing import Sequence
@@ -221,12 +220,10 @@ class StyleGuideManager:
         self.default_style_guide = StyleGuide(
             options, formatter, self.stats, decider=decider
         )
-        self.style_guides = list(
-            itertools.chain(
-                [self.default_style_guide],
-                self.populate_style_guides_with(options),
-            )
-        )
+        self.style_guides = [
+            self.default_style_guide,
+            *self.populate_style_guides_with(options),
+        ]
 
         self.style_guide_for = functools.lru_cache(maxsize=None)(
             self._style_guide_for