⚡ Bolt: [performance improvement] yEnc decoding using bytes builtins

verify_nzb.py

@@ -115,20 +115,39 @@ def _parse_yenc_attrs(line: bytes) -> dict[str, str]:
     return attrs
 
 
+_YENC_DECODE_TABLE = bytes((i - 42) % 256 for i in range(256))
+
 def _decode_yenc_lines(lines: Iterable[bytes]) -> bytes:
-    decoded = bytearray()
+    # ⚡ Bolt Optimization: Use C-backed bytes built-ins (find/translate)
+    # instead of a manual Python loop over every byte. This accelerates
+    # yEnc decoding by processing chunks in native C.
+    decoded_chunks = []
+
     for line in lines:
+        if b'=' not in line:
+            decoded_chunks.append(line.translate(_YENC_DECODE_TABLE))
+            continue
+
+        decoded = bytearray()
         index = 0
-        while index < len(line):
-            byte = line[index]
-            if byte == 61:
-                index += 1
-                if index >= len(line):
-                    raise ValueError("dangling yEnc escape")
-                byte = (line[index] - 64) % 256
-            decoded.append((byte - 42) % 256)
-            index += 1
-    return bytes(decoded)
+        length = len(line)
+        while index < length:
+            next_eq = line.find(b'=', index)
+            if next_eq == -1:
+                decoded.extend(line[index:])
+                break
+
+            decoded.extend(line[index:next_eq])
+            if next_eq + 1 >= length:
+                raise ValueError("dangling yEnc escape")
+
+            byte = (line[next_eq + 1] - 64) % 256
+            decoded.append(byte)
+            index = next_eq + 2
+
+        decoded_chunks.append(bytes(decoded).translate(_YENC_DECODE_TABLE))
+
+    return b"".join(decoded_chunks)
 
 
 def validate_yenc_body(lines: Iterable[bytes | str]) -> YencValidationResult: