diff --git a/nibabel/data.py b/nibabel/data.py
index c49580d09..8ea056d8e 100644
--- a/nibabel/data.py
+++ b/nibabel/data.py
@@ -87,8 +87,7 @@ def list_files(self, relative=True):
         for base, dirs, files in os.walk(self.base_path):
             if relative:
                 base = base[len(self.base_path) + 1 :]
-            for filename in files:
-                out_list.append(pjoin(base, filename))
+            out_list.extend(pjoin(base, filename) for filename in files)
         return out_list
 
 
diff --git a/nibabel/nicom/tests/test_dicomwrappers.py b/nibabel/nicom/tests/test_dicomwrappers.py
index 55c27df50..db3f66751 100755
--- a/nibabel/nicom/tests/test_dicomwrappers.py
+++ b/nibabel/nicom/tests/test_dicomwrappers.py
@@ -429,10 +429,9 @@ def fake_shape_dependents(
 
     class PrintBase:
         def __repr__(self):
-            attr_strs = []
-            for attr in dir(self):
-                if attr[0].isupper():
-                    attr_strs.append(f'{attr}={getattr(self, attr)}')
+            attr_strs = [
+                f'{attr}={getattr(self, attr)}' for attr in dir(self) if attr[0].isupper()
+            ]
             return f"{self.__class__.__name__}({', '.join(attr_strs)})"
 
     class DimIdxSeqElem(pydicom.Dataset):
diff --git a/nibabel/streamlines/tests/test_streamlines.py b/nibabel/streamlines/tests/test_streamlines.py
index 359cbc5e1..8811ddcfa 100644
--- a/nibabel/streamlines/tests/test_streamlines.py
+++ b/nibabel/streamlines/tests/test_streamlines.py
@@ -207,7 +207,7 @@ def test_save_tractogram_file(self):
 
     def test_save_empty_file(self):
         tractogram = Tractogram(affine_to_rasmm=np.eye(4))
-        for ext, cls in FORMATS.items():
+        for ext in FORMATS:
             with InTemporaryDirectory():
                 filename = 'streamlines' + ext
                 nib.streamlines.save(tractogram, filename)
@@ -216,7 +216,7 @@ def test_save_empty_file(self):
 
     def test_save_simple_file(self):
         tractogram = Tractogram(DATA['streamlines'], affine_to_rasmm=np.eye(4))
-        for ext, cls in FORMATS.items():
+        for ext in FORMATS:
             with InTemporaryDirectory():
                 filename = 'streamlines' + ext
                 nib.streamlines.save(tractogram, filename)
@@ -262,7 +262,7 @@ def test_save_complex_file(self):
     def test_save_sliced_tractogram(self):
         tractogram = Tractogram(DATA['streamlines'], affine_to_rasmm=np.eye(4))
         original_tractogram = tractogram.copy()
-        for ext, cls in FORMATS.items():
+        for ext in FORMATS:
             with InTemporaryDirectory():
                 filename = 'streamlines' + ext
                 nib.streamlines.save(tractogram[::2], filename)
@@ -283,7 +283,7 @@ def test_save_from_generator(self):
         tractogram = Tractogram(DATA['streamlines'], affine_to_rasmm=np.eye(4))
 
         # Just to create a generator
-        for ext, _ in FORMATS.items():
+        for ext in FORMATS:
             filtered = (s for s in tractogram.streamlines if True)
             lazy_tractogram = LazyTractogram(lambda: filtered, affine_to_rasmm=np.eye(4))
 
diff --git a/nibabel/testing/helpers.py b/nibabel/testing/helpers.py
index ae859d657..ad4bf258c 100644
--- a/nibabel/testing/helpers.py
+++ b/nibabel/testing/helpers.py
@@ -14,7 +14,7 @@
 def bytesio_filemap(klass):
     """Return bytes io filemap for this image class `klass`"""
     file_map = klass.make_file_map()
-    for name, fileholder in file_map.items():
+    for fileholder in file_map.values():
         fileholder.fileobj = BytesIO()
         fileholder.pos = 0
     return file_map
diff --git a/nibabel/tests/test_analyze.py b/nibabel/tests/test_analyze.py
index cb7b8d686..befc920f1 100644
--- a/nibabel/tests/test_analyze.py
+++ b/nibabel/tests/test_analyze.py
@@ -728,8 +728,8 @@ def test_data_hdr_cache(self):
         IC = self.image_class
         # save an image to a file map
         fm = IC.make_file_map()
-        for key, value in fm.items():
-            fm[key].fileobj = BytesIO()
+        for value in fm.values():
+            value.fileobj = BytesIO()
         shape = (2, 3, 4)
         data = np.arange(24, dtype=np.int8).reshape(shape)
         affine = np.eye(4)
@@ -831,7 +831,7 @@ def test_header_updating(self):
         hdr = img.header
         hdr.set_zooms((4, 5, 6))
         # Save / reload using bytes IO objects
-        for key, value in img.file_map.items():
+        for value in img.file_map.values():
             value.fileobj = BytesIO()
         img.to_file_map()
         hdr_back = img.from_file_map(img.file_map).header
@@ -842,7 +842,7 @@ def test_header_updating(self):
         assert_array_equal(hdr.get_zooms(), (2, 3, 4))
         # Modify affine in-place? Update on save.
         img.affine[0, 0] = 9
-        for key, value in img.file_map.items():
+        for value in img.file_map.values():
             value.fileobj = BytesIO()
         img.to_file_map()
         hdr_back = img.from_file_map(img.file_map).header
@@ -864,7 +864,7 @@ def test_pickle(self):
         assert_array_equal(img.get_fdata(), img2.get_fdata())
         assert img.header == img2.header
         # Save / reload using bytes IO objects
-        for key, value in img.file_map.items():
+        for value in img.file_map.values():
             value.fileobj = BytesIO()
         img.to_file_map()
         img_prox = img.from_file_map(img.file_map)
diff --git a/nibabel/tests/test_euler.py b/nibabel/tests/test_euler.py
index 1a781b8f1..4d251a16e 100644
--- a/nibabel/tests/test_euler.py
+++ b/nibabel/tests/test_euler.py
@@ -21,12 +21,8 @@
 FLOAT_EPS = np.finfo(np.float64).eps
 
 # Example rotations """
-eg_rots = []
 params = np.arange(-pi * 2, pi * 2.5, pi / 2)
-for x in params:
-    for y in params:
-        for z in params:
-            eg_rots.append((x, y, z))
+eg_rots = [(x, y, z) for x in params for y in params for z in params]
 
 
 def x_only(x):
diff --git a/nibabel/tests/test_filehandles.py b/nibabel/tests/test_filehandles.py
index 506a62375..c985d3544 100644
--- a/nibabel/tests/test_filehandles.py
+++ b/nibabel/tests/test_filehandles.py
@@ -33,8 +33,7 @@ def test_multiload():
         tmpdir = mkdtemp()
         fname = pjoin(tmpdir, 'test.img')
         save(img, fname)
-        for i in range(N):
-            imgs.append(load(fname))
+        imgs.extend(load(fname) for _ in range(N))
     finally:
         del img, imgs
         shutil.rmtree(tmpdir)
diff --git a/nibabel/tests/test_files_interface.py b/nibabel/tests/test_files_interface.py
index 07e394eca..b3562b608 100644
--- a/nibabel/tests/test_files_interface.py
+++ b/nibabel/tests/test_files_interface.py
@@ -28,7 +28,7 @@ def test_files_spatialimages():
     ]
     for klass in klasses:
         file_map = klass.make_file_map()
-        for key, value in file_map.items():
+        for value in file_map.values():
             assert value.filename is None
             assert value.fileobj is None
             assert value.pos == 0
@@ -41,7 +41,7 @@ def test_files_spatialimages():
             img = klass(arr.astype(np.float32), aff)
         else:
             img = klass(arr, aff)
-        for key, value in img.file_map.items():
+        for value in img.file_map.values():
             assert value.filename is None
             assert value.fileobj is None
             assert value.pos == 0
diff --git a/nibabel/tests/test_nifti1.py b/nibabel/tests/test_nifti1.py
index a3626f568..8eae0410e 100644
--- a/nibabel/tests/test_nifti1.py
+++ b/nibabel/tests/test_nifti1.py
@@ -820,7 +820,7 @@ def _qform_rt(self, img):
         hdr['qform_code'] = 3
         hdr['sform_code'] = 4
         # Save / reload using bytes IO objects
-        for key, value in img.file_map.items():
+        for value in img.file_map.values():
             value.fileobj = BytesIO()
         img.to_file_map()
         return img.from_file_map(img.file_map)
diff --git a/nibabel/tests/test_spm99analyze.py b/nibabel/tests/test_spm99analyze.py
index ada92d3b0..26098d8ed 100644
--- a/nibabel/tests/test_spm99analyze.py
+++ b/nibabel/tests/test_spm99analyze.py
@@ -423,7 +423,7 @@ def test_mat_read(self):
         aff = np.diag([2, 3, 4, 1])  # no LR flip in affine
         img = img_klass(arr, aff)
         fm = img.file_map
-        for key, value in fm.items():
+        for value in fm.values():
             value.fileobj = BytesIO()
         # Test round trip
         img.to_file_map()
@@ -475,7 +475,7 @@ def test_none_affine(self):
         img = img_klass(np.zeros((2, 3, 4)), None)
         aff = img.header.get_best_affine()
         # Save / reload using bytes IO objects
-        for key, value in img.file_map.items():
+        for value in img.file_map.values():
             value.fileobj = BytesIO()
         img.to_file_map()
         img_back = img.from_file_map(img.file_map)
diff --git a/pyproject.toml b/pyproject.toml
index 22be5f917..748dc12ce 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -123,6 +123,7 @@ select = [
     "FLY",
     "FURB",
     "I",
+    "PERF",
     "PIE",
     "PLE",
     "PT",
@@ -146,6 +147,7 @@ ignore = [
     "C401",
     "C408",
     "C416",
+    "PERF203",
     "PIE790",
     "PT004",
     "PT007",