diff --git a/examples/deepzoom/deepzoom_multiserver.py b/examples/deepzoom/deepzoom_multiserver.py
index 46f51743..8142b6fe 100755
--- a/examples/deepzoom/deepzoom_multiserver.py
+++ b/examples/deepzoom/deepzoom_multiserver.py
@@ -42,7 +42,7 @@
 if os.name == 'nt':
     _dll_path = os.getenv('OPENSLIDE_PATH')
     if _dll_path is not None:
-        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined]
+        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined,unused-ignore]  # noqa: E501
             import openslide
     else:
         import openslide
diff --git a/examples/deepzoom/deepzoom_server.py b/examples/deepzoom/deepzoom_server.py
index f57579e9..fb9efbf1 100755
--- a/examples/deepzoom/deepzoom_server.py
+++ b/examples/deepzoom/deepzoom_server.py
@@ -42,7 +42,7 @@
 if os.name == 'nt':
     _dll_path = os.getenv('OPENSLIDE_PATH')
     if _dll_path is not None:
-        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined]
+        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined,unused-ignore]  # noqa: E501
             import openslide
     else:
         import openslide
diff --git a/examples/deepzoom/deepzoom_tile.py b/examples/deepzoom/deepzoom_tile.py
index 05e4d9a7..6f52324d 100755
--- a/examples/deepzoom/deepzoom_tile.py
+++ b/examples/deepzoom/deepzoom_tile.py
@@ -48,7 +48,7 @@
 if os.name == 'nt':
     _dll_path = os.getenv('OPENSLIDE_PATH')
     if _dll_path is not None:
-        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined]
+        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined,unused-ignore]  # noqa: E501
             import openslide
     else:
         import openslide
@@ -382,6 +382,19 @@ def _shutdown(self) -> None:
 
 
 if __name__ == '__main__':
+    try:
+        # Python 3.13+
+        available_cpus = os.process_cpu_count()  # type: ignore[attr-defined]
+    except AttributeError:
+        try:
+            # Linux
+            available_cpus = len(
+                os.sched_getaffinity(0)  # type: ignore[attr-defined,unused-ignore]
+            )
+        except AttributeError:
+            # default
+            available_cpus = 4
+
     parser = ArgumentParser(usage='%(prog)s [options] <SLIDE>')
     parser.add_argument(
         '-B',
@@ -433,8 +446,8 @@ def _shutdown(self) -> None:
         metavar='COUNT',
         dest='workers',
         type=int,
-        default=4,
-        help='number of worker processes to start [4]',
+        default=available_cpus,
+        help=f'number of worker processes to start [{available_cpus}]',
     )
     parser.add_argument(
         '-o',
diff --git a/tests/common.py b/tests/common.py
index 28bc8bfb..ca034195 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -30,7 +30,7 @@
     # environment.
     _dll_path = os.getenv('OPENSLIDE_PATH')
     if _dll_path is not None:
-        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined]
+        with os.add_dll_directory(_dll_path):  # type: ignore[attr-defined,unused-ignore]  # noqa: E501
             import openslide  # noqa: F401  module-imported-but-unused