From 35753efa356a5f0d47c1e5a6560221b01b9d42cb Mon Sep 17 00:00:00 2001
From: Damian Shaw <damian.peter.shaw@gmail.com>
Date: Mon, 26 Oct 2026 16:02:12 -0400
Subject: [PATCH] Reuse plain frame bodies during serialization

---
 CHANGELOG.rst           |  2 +-
 src/hyperframe/frame.py | 14 ++++++++++++++
 tests/test_frames.py    | 12 ++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 750102f..c657aa9 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -19,7 +19,7 @@ dev
 
 **Bugfixes**
 
--
+- Avoided copying unmodified DATA and HEADERS bodies during serialization.
 
 6.1.0 (2025-01-22)
 ------------------
diff --git a/src/hyperframe/frame.py b/src/hyperframe/frame.py
index 5bab673..bd6e127 100644
--- a/src/hyperframe/frame.py
+++ b/src/hyperframe/frame.py
@@ -304,6 +304,10 @@ def serialize_body(self) -> bytes:
         padding = b"\0" * self.pad_length
         if isinstance(self.data, memoryview):
             self.data = self.data.tobytes()
+
+        if type(self.data) is bytes and type(padding_data) is bytes and not padding_data and not padding:
+            return self.data
+
         return b"".join([padding_data, self.data, padding])
 
     def parse_body(self, data: memoryview) -> None:
@@ -748,6 +752,16 @@ def serialize_body(self) -> bytes:
         else:
             priority_data = b""
 
+        if (
+            type(self.data) is bytes
+            and type(padding_data) is bytes
+            and not padding_data
+            and type(priority_data) is bytes
+            and not priority_data
+            and not padding
+        ):
+            return self.data
+
         return b"".join([padding_data, priority_data, self.data, padding])
 
     def parse_body(self, data: memoryview) -> None:
diff --git a/tests/test_frames.py b/tests/test_frames.py
index b683354..20b7a61 100644
--- a/tests/test_frames.py
+++ b/tests/test_frames.py
@@ -142,6 +142,12 @@ def test_data_frame_serializes_properly(self, data):
         s = f.serialize()
         assert s == self.payload
 
+    def test_plain_data_frame_reuses_bytes_body(self):
+        data = b'testdata'
+        f = DataFrame(1, data)
+
+        assert f.serialize_body() is data
+
     def test_data_frame_with_padding_serializes_properly(self):
         f = DataFrame(1)
         f.flags = set(['END_STREAM', 'PADDED'])
@@ -791,6 +797,12 @@ def test_headers_frame_serializes_properly(self):
             b'hello world'
         )
 
+    def test_plain_headers_frame_reuses_bytes_body(self):
+        data = b'hello world'
+        f = HeadersFrame(1, data)
+
+        assert f.serialize_body() is data
+
     def test_headers_frame_parses_properly(self):
         s = (
             b'\x00\x00\x0B\x01\x05\x00\x00\x00\x01' +