diff --git a/src/_pytest/assertion/rewrite.py b/src/_pytest/assertion/rewrite.py
index 8c85240ef..99416aed2 100644
--- a/src/_pytest/assertion/rewrite.py
+++ b/src/_pytest/assertion/rewrite.py
@@ -554,6 +554,7 @@ def set_location(node, lineno, col_offset):
     return node
 
 
+@functools.lru_cache(maxsize=1)
 def _get_assertion_exprs(src: bytes) -> Dict[int, str]:
     """Return a mapping from {lineno: "assertion test expression"}."""
     ret: Dict[int, str] = {}
@@ -675,10 +676,6 @@ class AssertionRewriter(ast.NodeVisitor):
             self.enable_assertion_pass_hook = False
         self.source = source
 
-    @functools.lru_cache(maxsize=1)
-    def _assert_expr_to_lineno(self) -> Dict[int, str]:
-        return _get_assertion_exprs(self.source)
-
     def run(self, mod: ast.Module) -> None:
         """Find all assert statements in *mod* and rewrite them."""
         if not mod.body:
@@ -906,7 +903,7 @@ class AssertionRewriter(ast.NodeVisitor):
 
             # Passed
             fmt_pass = self.helper("_format_explanation", msg)
-            orig = self._assert_expr_to_lineno()[assert_.lineno]
+            orig = _get_assertion_exprs(self.source)[assert_.lineno]
             hook_call_pass = ast.Expr(
                 self.helper(
                     "_call_assertion_pass",
diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index 0af41215b..de5b80e30 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -522,7 +522,6 @@ class PytestPluginManager(PluginManager):
                 if x.is_dir():
                     self._getconftestmodules(x, importmode, rootpath)
 
-    @lru_cache(maxsize=128)
     def _getconftestmodules(
         self, path: Path, importmode: Union[str, ImportMode], rootpath: Path
     ) -> List[types.ModuleType]:
@@ -534,12 +533,19 @@ class PytestPluginManager(PluginManager):
         else:
             directory = path
 
+        # Optimization: avoid repeated searches in the same directory.
+        # Assumes always called with same importmode and rootpath.
+        existing_clist = self._dirpath2confmods.get(directory)
+        if existing_clist:
+            return existing_clist
+
         # XXX these days we may rather want to use config.rootpath
         # and allow users to opt into looking into the rootdir parent
         # directories instead of requiring to specify confcutdir.
         clist = []
+        confcutdir_parents = self._confcutdir.parents if self._confcutdir else []
         for parent in reversed((directory, *directory.parents)):
-            if self._confcutdir and parent in self._confcutdir.parents:
+            if parent in confcutdir_parents:
                 continue
             conftestpath = parent / "conftest.py"
             if conftestpath.is_file():