optimize message type detection for performance

sources/pg_replication/helpers.py

@@ -603,20 +603,20 @@ def process_msg(self, msg: ReplicationMessage) -> None:
         - `target_batch_size` is reached
         - a table's schema has changed
         """
-        op = (msg.payload[:1]).decode("utf-8")
-        if op == "B":
-            self.last_commit_ts = Begin(msg.payload).commit_ts
-        elif op == "C":
-            self.process_commit(msg)
-        elif op == "R":
-            self.process_relation(Relation(msg.payload))
-        elif op == "I":
+        op = msg.payload[:1]
+        if op == b"I":
             self.process_change(Insert(msg.payload), msg.data_start)
-        elif op == "U":
+        elif op == b"U":
             self.process_change(Update(msg.payload), msg.data_start)
-        elif op == "D":
+        elif op == b"D":
             self.process_change(Delete(msg.payload), msg.data_start)
-        elif op == "T":
+        elif op == b"B":
+            self.last_commit_ts = Begin(msg.payload).commit_ts
+        elif op == b"C":
+            self.process_commit(msg)
+        elif op == b"R":
+            self.process_relation(Relation(msg.payload))
+        elif op == b"T":
             logger.warning(
                 "The truncate operation is currently not supported. "
                 "Truncate replication messages are ignored."