Experiment with pooled xfer buffer.

src/NTwain/DataTransferredEventArgs.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Buffers;
+
+namespace NTwain
+{
+  public class DataTransferredEventArgs : EventArgs, IDisposable
+  {
+    /// <summary>
+    /// Ctor for pooled data and the pool to clean it up.
+    /// </summary>
+    /// <param name="pool"></param>
+    /// <param name="data"></param>
+    internal DataTransferredEventArgs(ArrayPool<byte>? pool, byte[]? data)
+    {
+      _pool = pool;
+      Data = data;
+    }
+
+
+    bool _disposed;
+    private readonly ArrayPool<byte>? _pool;
+
+    /// <summary>
+    /// The complete file data if the transfer was done
+    /// through memory. IMPORTANT: The data held
+    /// in this array will no longer be valid once
+    /// this event arg has been disposed.
+    /// </summary>
+    public byte[]? Data { get; private set; }
+
+
+
+    public void Dispose()
+    {
+      if (!_disposed)
+      {
+        if (_pool != null && Data != null)
+        {
+          _pool.Return(Data);
+          Data = null;
+        }
+        _disposed = true;
+      }
+    }
+  }
+}

src/NTwain/TwainAppSession.Xfers.cs

@@ -1,6 +1,7 @@
 using NTwain.Data;
 using NTwain.Triplets;
 using System;
+using System.Buffers;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -12,6 +13,12 @@ namespace NTwain
 
   partial class TwainAppSession
   {
+    // experiment using array pool for things transferred in memory.
+    // this can pool up to a "normal" max of legal size paper in 24 bit at 300 dpi (~31MB)
+    // so the array max is made with 32 MB. Typical usage should be a lot less.
+    static readonly ArrayPool<byte> XferMemPool = ArrayPool<byte>.Create(32505856, 4);
+
+
     /// <summary>
     /// Start the transfer loop.
     /// This should be called after receiving