diff --git a/main/DDF/EscherBSERecord.cs b/main/DDF/EscherBSERecord.cs
index c355603e4..da30605e5 100644
--- a/main/DDF/EscherBSERecord.cs
+++ b/main/DDF/EscherBSERecord.cs
@@ -349,7 +349,7 @@ public override String ToString()
                 {
                     HexDump.Dump(this._remainingData, 0, b, 0);
                     //extraData = b.ToString();
-                    extraData = Encoding.UTF8.GetString(b.ToArray());
+                    extraData = Encoding.UTF8.GetString(b.GetBuffer(), 0, (int)b.Length);
                 }
                 catch (Exception e)
                 {
diff --git a/main/DDF/EscherBlipWMFRecord.cs b/main/DDF/EscherBlipWMFRecord.cs
index c75b07504..a528a97a5 100644
--- a/main/DDF/EscherBlipWMFRecord.cs
+++ b/main/DDF/EscherBlipWMFRecord.cs
@@ -287,7 +287,7 @@ public override String ToString()
                 {
                     HexDump.Dump(this.field_12_data, 0, b, 0);
                     //extraData = b.ToString();
-                    extraData = Encoding.UTF8.GetString(b.ToArray());
+                    extraData = Encoding.UTF8.GetString(b.GetBuffer(), 0, (int)b.Length);
                 }
                 catch (Exception e)
                 {
diff --git a/main/HPSF/MutableSection.cs b/main/HPSF/MutableSection.cs
index 23a74417f..2356eee06 100644
--- a/main/HPSF/MutableSection.cs
+++ b/main/HPSF/MutableSection.cs
@@ -426,23 +426,25 @@ public int Write(Stream out1)
                     propertyListStream.Flush();
 
                     /* Write the section: */
-                    byte[] pb1 = propertyListStream.ToArray();
-                    byte[] pb2 = propertyStream.ToArray();
+                    byte[] pb1 = propertyListStream.GetBuffer();
+                    byte[] pb2 = propertyStream.GetBuffer();
+                    int pb1Length = (int)propertyListStream.Length;
+                    int pb2Length = (int)propertyStream.Length;
 
                     /* Write the section's Length: */
                     TypeWriter.WriteToStream(out1, LittleEndianConsts.INT_SIZE * 2 +
-                                                  pb1.Length + pb2.Length);
+                                                  pb1Length + pb2Length);
 
                     /* Write the section's number of properties: */
                     TypeWriter.WriteToStream(out1, PropertyCount);
 
                     /* Write the property list: */
-                    out1.Write(pb1, 0, pb1.Length);
+                    out1.Write(pb1, 0, pb1Length);
 
                     /* Write the properties: */
-                    out1.Write(pb2, 0, pb2.Length);
+                    out1.Write(pb2, 0, pb2Length);
 
-                    int streamLength = LittleEndianConsts.INT_SIZE * 2 + pb1.Length + pb2.Length;
+                    int streamLength = LittleEndianConsts.INT_SIZE * 2 + pb1Length + pb2Length;
                     return streamLength;
                 }
             }
diff --git a/main/HSSF/Record/Crypto/Biff8EncryptionKey.cs b/main/HSSF/Record/Crypto/Biff8EncryptionKey.cs
index 13631e065..45fc9fb03 100644
--- a/main/HSSF/Record/Crypto/Biff8EncryptionKey.cs
+++ b/main/HSSF/Record/Crypto/Biff8EncryptionKey.cs
@@ -138,10 +138,9 @@ internal RC4 CreateRC4(int keyBlockNo)
                 using (MemoryStream baos = RecyclableMemory.GetStream(4))
                 {
                     new LittleEndianOutputStream(baos).WriteInt(keyBlockNo);
-                    byte[] baosToArray = baos.ToArray();
-                    byte[] data = new byte[baosToArray.Length + _keyDigest.Length];
+                    byte[] data = new byte[(int)baos.Length + _keyDigest.Length];
                     Array.Copy(_keyDigest, 0, data, 0, _keyDigest.Length);
-                    Array.Copy(baosToArray, 0, data, _keyDigest.Length, baosToArray.Length);
+                    Array.Copy(baos.GetBuffer(), 0, data, _keyDigest.Length, (int)baos.Length);
 
                     byte[] digest = md5.ComputeHash(data);
                     return new RC4(digest);
diff --git a/main/POIFS/Storage/HeaderBlockWriter.cs b/main/POIFS/Storage/HeaderBlockWriter.cs
index ccf741af1..4fe1e433f 100644
--- a/main/POIFS/Storage/HeaderBlockWriter.cs
+++ b/main/POIFS/Storage/HeaderBlockWriter.cs
@@ -169,7 +169,7 @@ public void WriteBlock(ByteBuffer block)
             {
                 _header_block.WriteData(ms);
 
-                block.Write(ms.ToArray());
+                block.Write(ms.GetBuffer(), 0, (int)ms.Length);
             }
         }
 
@@ -180,8 +180,7 @@ public void WriteBlock(byte[] block)
             {
                 _header_block.WriteData(ms);
 
-                byte[] temp = ms.ToArray();
-                Array.Copy(temp, 0, block, 0, temp.Length);
+                Array.Copy(ms.GetBuffer(), 0, block, 0, (int)ms.Length);
             }
         }
     }
diff --git a/main/Util/HexDump.cs b/main/Util/HexDump.cs
index 08790bb23..5836eded7 100644
--- a/main/Util/HexDump.cs
+++ b/main/Util/HexDump.cs
@@ -206,8 +206,7 @@ public static void Dump(Stream inStream, int start, int bytesToDump)
                             stream.WriteByte((byte)c);
                     }
                 }
-                byte[] data = stream.ToArray();
-                Dump(data, 0L, null, start, data.Length);
+                Dump(stream.GetBuffer(), 0L, null, start, (int)stream.Length);
             }
         }
 
@@ -318,8 +317,7 @@ public static void Dump(Stream in1, Stream out1, int start, int bytesToDump )
                 }
             }
 
-            byte[] data = buf.ToArray();
-            Dump(data, 0, out1, start, data.Length);
+            Dump(buf.GetBuffer(), 0, out1, start, (int)buf.Length);
         }
 
         /// <summary>
diff --git a/ooxml/POIFS/Crypt/Agile/AgileEncryptor.cs b/ooxml/POIFS/Crypt/Agile/AgileEncryptor.cs
index a4166ebc8..31344d65f 100644
--- a/ooxml/POIFS/Crypt/Agile/AgileEncryptor.cs
+++ b/ooxml/POIFS/Crypt/Agile/AgileEncryptor.cs
@@ -320,7 +320,7 @@ protected void marshallEncryptionDocument(EncryptionDocument ed, LittleEndianByt
                 byte[] buf = Encoding.UTF8.GetBytes("<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\r\n");
                 bos.Write(buf, 0, buf.Length);
                 ed.Save(bos);
-                os.Write(bos.ToArray());
+                os.Write(bos.GetBuffer(), 0, (int)bos.Length);
             } catch (IOException e) {
                 throw new EncryptedDocumentException("error marshalling encryption info document", e);
             }
diff --git a/openxml4Net/OPC/OPCPackage.cs b/openxml4Net/OPC/OPCPackage.cs
index 6443d72cc..cd8b39019 100644
--- a/openxml4Net/OPC/OPCPackage.cs
+++ b/openxml4Net/OPC/OPCPackage.cs
@@ -1023,7 +1023,7 @@ public PackagePart CreatePart(PackagePartName partName, String contentType,
                         return null;
                     }
 
-                    partOutput.Write(content.ToArray(), 0, (int)content.Length);
+                    partOutput.Write(content.TryGetBuffer(out var buf) ? buf.Array : content.ToArray(), 0, (int)content.Length);
                     partOutput.Close();
 
                 }