diff --git a/pyproject.toml b/pyproject.toml
index a4b43d3b04..eadd0e628f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -152,6 +152,8 @@ extend-select = [
   "C4",          # flake8-comprehensions
   "EM",          # flake8-errmsg
   "ICN",         # flake8-import-conventions
+  "ISC",         # flake8-implicit-str-concat
+  "PERF",        # Perflint
   "PGH",         # pygrep-hooks
   "PIE",         # flake8-pie
   "PL",          # pylint
diff --git a/tests/test_class_sh_basic.py b/tests/test_class_sh_basic.py
index 18f0b0646e..aaea87b8f3 100644
--- a/tests/test_class_sh_basic.py
+++ b/tests/test_class_sh_basic.py
@@ -112,8 +112,8 @@ def test_pass_unique_ptr_disowns(pass_f, rtrn_f, expected):
         pass_f(obj)
     assert str(exc_info.value) == (
         "Missing value for wrapped C++ type"
-        + " `pybind11_tests::class_sh_basic::atyp`:"
-        + " Python instance was disowned."
+        " `pybind11_tests::class_sh_basic::atyp`:"
+        " Python instance was disowned."
     )
 
 
diff --git a/tests/test_iostream.py b/tests/test_iostream.py
index 00b24ab706..791b9e0483 100644
--- a/tests/test_iostream.py
+++ b/tests/test_iostream.py
@@ -288,11 +288,7 @@ def test_redirect_both(capfd):
 def test_threading():
     with m.ostream_redirect(stdout=True, stderr=False):
         # start some threads
-        threads = []
-
-        # start some threads
-        for _j in range(20):
-            threads.append(m.TestThread())
+        threads = [m.TestThread() for _j in range(20)]
 
         # give the threads some time to fail
         threads[0].sleep()
diff --git a/tests/test_stl_binders.py b/tests/test_stl_binders.py
index 9856ba462b..518f2df2b6 100644
--- a/tests/test_stl_binders.py
+++ b/tests/test_stl_binders.py
@@ -258,7 +258,7 @@ def test_noncopyable_containers():
             assert nvnc[i][j].value == j + 1
 
     # Note: maps do not have .values()
-    for _, v in nvnc.items():
+    for v in nvnc.values():
         for i, j in enumerate(v, start=1):
             assert j.value == i
 
@@ -269,7 +269,7 @@ def test_noncopyable_containers():
             assert nmnc[i][j].value == 10 * j
 
     vsum = 0
-    for _, v_o in nmnc.items():
+    for v_o in nmnc.values():
         for k_i, v_i in v_o.items():
             assert v_i.value == 10 * k_i
             vsum += v_i.value
@@ -283,7 +283,7 @@ def test_noncopyable_containers():
             assert numnc[i][j].value == 10 * j
 
     vsum = 0
-    for _, v_o in numnc.items():
+    for v_o in numnc.values():
         for k_i, v_i in v_o.items():
             assert v_i.value == 10 * k_i
             vsum += v_i.value