diff --git a/AyCode.Core/Serializers/Binaries/AcBinarySerializer.BinarySerializationContext.cs b/AyCode.Core/Serializers/Binaries/AcBinarySerializer.BinarySerializationContext.cs
index 3a8fea7..5b7e5c5 100644
--- a/AyCode.Core/Serializers/Binaries/AcBinarySerializer.BinarySerializationContext.cs
+++ b/AyCode.Core/Serializers/Binaries/AcBinarySerializer.BinarySerializationContext.cs
@@ -388,11 +388,21 @@ public static partial class AcBinarySerializer
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void WriteByte(byte value)
         {
-            if (_position >= _bufferEnd)
-                Output.Grow(ref _buffer, ref _position, ref _bufferEnd, 1);
+            if (_position >= _bufferEnd) GrowOne();
             _buffer[_position++] = value;
         }
 
+        /// <summary>
+        /// Cold-path single-byte grow helper. Outlined from the hot-path 1-byte writers
+        /// (<see cref="WriteByte"/>, <see cref="WriteVarUInt"/> / <see cref="WriteVarULong"/> fast-paths)
+        /// so the inliner cost-models the hot path WITHOUT the 4-ref-arg <c>Output.Grow</c> call's
+        /// argument-prep IL. This keeps the per-property hot-path tight enough for AOT to inline the
+        /// write into the source-gen <c>WriteProperties</c> body across many call-sites — the cumulative
+        /// gain shows up on graph-heavy cells where every leaf serialises ~6 primitive properties.
+        /// </summary>
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private void GrowOne() => Output.Grow(ref _buffer, ref _position, ref _bufferEnd, 1);
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void WriteTwoBytes(byte b1, byte b2)
         {
@@ -464,8 +474,7 @@ public static partial class AcBinarySerializer
             //if (FastWire) { WriteRaw(value); return; }
             if (value < 0x80)
             {
-                if (_position >= _bufferEnd)
-                    Output.Grow(ref _buffer, ref _position, ref _bufferEnd, 1);
+                if (_position >= _bufferEnd) GrowOne();
                 _buffer[_position++] = (byte)value;
                 return;
             }
@@ -531,8 +540,7 @@ public static partial class AcBinarySerializer
             //if (FastWire) { WriteRaw(value); return; }
             if (value < 0x80)
             {
-                if (_position >= _bufferEnd)
-                    Output.Grow(ref _buffer, ref _position, ref _bufferEnd, 1);
+                if (_position >= _bufferEnd) GrowOne();
                 _buffer[_position++] = (byte)value;
                 return;
             }