Adding test_watermarking_speed

tests/test_writer.py

@@ -1536,6 +1536,27 @@ def test_watermark():
     assert len(b.getvalue()) < 2.1 * 1024 * 1024
 
 
+@pytest.mark.enable_socket()
+@pytest.mark.timeout(45)  # this was > x2 slower before PR #2086
+def test_watermarking_speed():
+    url = "https://github.com/py-pdf/pypdf/files/11985889/bg.pdf"
+    name = "bgwatermark.pdf"
+    reader = PdfReader(BytesIO(get_data_from_url(url, name=name)))
+    url = "https://arxiv.org/pdf/2201.00214.pdf"
+    name = "src_doc.pdf"
+    writer = PdfWriter(clone_from=BytesIO(get_data_from_url(url, name=name)))
+    for p in writer.pages:
+        p.merge_page(reader.pages[0], over=False)
+
+    assert isinstance(p["/Contents"], ArrayObject)
+    assert isinstance(p["/Contents"][0], IndirectObject)
+
+    b = BytesIO()
+    writer.write(b)
+    print(len(b.getvalue()) / 1024 / 1024)
+    assert len(b.getvalue()) < 2.5 * 1024 * 1024
+
+
 @pytest.mark.enable_socket()
 def test_da_missing_in_annot():
     url = "https://github.com/py-pdf/pypdf/files/12136285/Building.Division.Permit.Application.pdf"