diff --git a/projects/RabbitMQ.Client/client/api/ConnectionFactory.cs b/projects/RabbitMQ.Client/client/api/ConnectionFactory.cs
index 5690207582..15d5b07e1c 100644
--- a/projects/RabbitMQ.Client/client/api/ConnectionFactory.cs
+++ b/projects/RabbitMQ.Client/client/api/ConnectionFactory.cs
@@ -329,14 +329,16 @@ public Uri Uri
         public IAuthMechanismFactory AuthMechanismFactory(IList<string> mechanismNames)
         {
             // Our list is in order of preference, the server one is not.
-            foreach (IAuthMechanismFactory factory in AuthMechanisms)
+            for (int index = 0; index < AuthMechanisms.Count; index++)
             {
+                IAuthMechanismFactory factory = AuthMechanisms[index];
                 string factoryName = factory.Name;
                 if (mechanismNames.Any<string>(x => string.Equals(x, factoryName, StringComparison.OrdinalIgnoreCase)))
                 {
                     return factory;
                 }
             }
+
             return null;
         }
 
diff --git a/projects/RabbitMQ.Client/client/impl/AutorecoveringConnection.cs b/projects/RabbitMQ.Client/client/impl/AutorecoveringConnection.cs
index c3d1593ecd..1f11a61a3c 100644
--- a/projects/RabbitMQ.Client/client/impl/AutorecoveringConnection.cs
+++ b/projects/RabbitMQ.Client/client/impl/AutorecoveringConnection.cs
@@ -67,15 +67,15 @@ internal sealed class AutorecoveringConnection : IAutorecoveringConnection
 
         private readonly object _recordedEntitiesLock = new object();
 
-        private readonly IDictionary<string, RecordedExchange> _recordedExchanges = new Dictionary<string, RecordedExchange>();
+        private readonly Dictionary<string, RecordedExchange> _recordedExchanges = new Dictionary<string, RecordedExchange>();
 
-        private readonly IDictionary<string, RecordedQueue> _recordedQueues = new Dictionary<string, RecordedQueue>();
+        private readonly Dictionary<string, RecordedQueue> _recordedQueues = new Dictionary<string, RecordedQueue>();
 
-        private readonly IDictionary<RecordedBinding, byte> _recordedBindings = new Dictionary<RecordedBinding, byte>();
+        private readonly Dictionary<RecordedBinding, byte> _recordedBindings = new Dictionary<RecordedBinding, byte>();
 
-        private readonly IDictionary<string, RecordedConsumer> _recordedConsumers = new Dictionary<string, RecordedConsumer>();
+        private readonly Dictionary<string, RecordedConsumer> _recordedConsumers = new Dictionary<string, RecordedConsumer>();
 
-        private readonly ICollection<AutorecoveringModel> _models = new List<AutorecoveringModel>();
+        private readonly List<AutorecoveringModel> _models = new List<AutorecoveringModel>();
 
         private EventHandler<ConnectionBlockedEventArgs> _recordedBlockedEventHandlers;
         private EventHandler<ShutdownEventArgs> _recordedShutdownEventHandlers;
@@ -485,12 +485,11 @@ public void DeleteRecordedBinding(RecordedBinding rb)
 
         public RecordedConsumer DeleteRecordedConsumer(string consumerTag)
         {
-            RecordedConsumer rc = null;
+            RecordedConsumer rc;
             lock (_recordedEntitiesLock)
             {
-                if (_recordedConsumers.ContainsKey(consumerTag))
+                if (_recordedConsumers.TryGetValue(consumerTag, out rc))
                 {
-                    rc = _recordedConsumers[consumerTag];
                     _recordedConsumers.Remove(consumerTag);
                 }
             }
@@ -912,10 +911,12 @@ private void PropagateQueueNameChangeToBindings(string oldName, string newName)
         {
             lock (_recordedBindings)
             {
-                IEnumerable<RecordedBinding> bs = _recordedBindings.Keys.Where(b => b.Destination.Equals(oldName));
-                foreach (RecordedBinding b in bs)
+                foreach (RecordedBinding b in _recordedBindings.Keys)
                 {
-                    b.Destination = newName;
+                    if (b.Destination.Equals(oldName))
+                    {
+                        b.Destination = newName;
+                    }
                 }
             }
         }
@@ -924,21 +925,22 @@ private void PropagateQueueNameChangeToConsumers(string oldName, string newName)
         {
             lock (_recordedConsumers)
             {
-                IEnumerable<KeyValuePair<string, RecordedConsumer>> cs = _recordedConsumers.
-                    Where(pair => pair.Value.Queue.Equals(oldName));
-                foreach (KeyValuePair<string, RecordedConsumer> c in cs)
+                foreach (KeyValuePair<string, RecordedConsumer> c in _recordedConsumers)
                 {
-                    c.Value.Queue = newName;
+                    if (c.Value.Queue.Equals(oldName))
+                    {
+                        c.Value.Queue = newName;
+                    }
                 }
             }
         }
 
         private void RecoverBindings()
         {
-            IDictionary<RecordedBinding, byte> recordedBindingsCopy = null;
+            Dictionary<RecordedBinding, byte> recordedBindingsCopy;
             lock (_recordedBindings)
             {
-                recordedBindingsCopy = _recordedBindings.ToDictionary(e => e.Key, e => e.Value);
+                recordedBindingsCopy = new Dictionary<RecordedBinding, byte>(_recordedBindings);
             }
 
             foreach (RecordedBinding b in recordedBindingsCopy.Keys)
@@ -1031,10 +1033,10 @@ private void RecoverConsumers()
                 throw new ObjectDisposedException(GetType().FullName);
             }
 
-            IDictionary<string, RecordedConsumer> recordedConsumersCopy = null;
+            Dictionary<string, RecordedConsumer> recordedConsumersCopy;
             lock (_recordedConsumers)
             {
-                recordedConsumersCopy = _recordedConsumers.ToDictionary(e => e.Key, e => e.Value);
+                recordedConsumersCopy = new Dictionary<string, RecordedConsumer>(_recordedConsumers);
             }
 
             foreach (KeyValuePair<string, RecordedConsumer> pair in recordedConsumersCopy)
@@ -1091,10 +1093,10 @@ private void RecoverEntities()
 
         private void RecoverExchanges()
         {
-            IDictionary<string, RecordedExchange> recordedExchangesCopy = null;
+            Dictionary<string, RecordedExchange> recordedExchangesCopy;
             lock (_recordedEntitiesLock)
             {
-                recordedExchangesCopy = _recordedExchanges.ToDictionary(e => e.Key, e => e.Value);
+                recordedExchangesCopy = new Dictionary<string, RecordedExchange>(_recordedExchanges);
             }
 
             foreach (RecordedExchange rx in recordedExchangesCopy.Values)
@@ -1125,10 +1127,10 @@ private void RecoverModels()
 
         private void RecoverQueues()
         {
-            IDictionary<string, RecordedQueue> recordedQueuesCopy = null;
+            Dictionary<string, RecordedQueue> recordedQueuesCopy;
             lock (_recordedEntitiesLock)
             {
-                recordedQueuesCopy = _recordedQueues.ToDictionary(entry => entry.Key, entry => entry.Value);
+                recordedQueuesCopy = new Dictionary<string, RecordedQueue>(_recordedQueues);
             }
 
             foreach (KeyValuePair<string, RecordedQueue> pair in recordedQueuesCopy)
diff --git a/projects/RabbitMQ.Client/client/impl/BasicProperties.cs b/projects/RabbitMQ.Client/client/impl/BasicProperties.cs
index 05ffda72a2..dc7d7f6035 100644
--- a/projects/RabbitMQ.Client/client/impl/BasicProperties.cs
+++ b/projects/RabbitMQ.Client/client/impl/BasicProperties.cs
@@ -284,11 +284,7 @@ public override object Clone()
             var clone = MemberwiseClone() as BasicProperties;
             if (IsHeadersPresent())
             {
-                clone.Headers = new Dictionary<string, object>();
-                foreach (KeyValuePair<string, object> entry in Headers)
-                {
-                    clone.Headers[entry.Key] = entry.Value;
-                }
+                clone.Headers = new Dictionary<string, object>(Headers);
             }
 
             return clone;
diff --git a/projects/RabbitMQ.Client/client/impl/Connection.cs b/projects/RabbitMQ.Client/client/impl/Connection.cs
index aead6f6c92..24802bb3e1 100644
--- a/projects/RabbitMQ.Client/client/impl/Connection.cs
+++ b/projects/RabbitMQ.Client/client/impl/Connection.cs
@@ -730,10 +730,9 @@ public void PrettyPrintShutdownReport()
             {
                 Console.Error.WriteLine(
 "Log of errors while closing connection {0}:", this);
-                foreach (ShutdownReportEntry entry in ShutdownReport)
+                for (int index = 0; index < ShutdownReport.Count; index++)
                 {
-                    Console.Error.WriteLine(
-entry.ToString());
+                    Console.Error.WriteLine(ShutdownReport[index].ToString());
                 }
             }
         }
diff --git a/projects/RabbitMQ.Client/client/impl/ContentHeaderPropertyReader.cs b/projects/RabbitMQ.Client/client/impl/ContentHeaderPropertyReader.cs
index d9d3cf9672..35cb86d76c 100644
--- a/projects/RabbitMQ.Client/client/impl/ContentHeaderPropertyReader.cs
+++ b/projects/RabbitMQ.Client/client/impl/ContentHeaderPropertyReader.cs
@@ -45,7 +45,7 @@
 
 namespace RabbitMQ.Client.Impl
 {
-    struct ContentHeaderPropertyReader
+    internal struct ContentHeaderPropertyReader
     {
         private ushort m_bitCount;
         private ushort m_flagWord;
@@ -143,9 +143,9 @@ public string ReadShortstr()
         }
 
         /// <returns>A type of <seealso cref="System.Collections.Generic.IDictionary{TKey,TValue}"/>.</returns>
-        public IDictionary<string, object> ReadTable()
+        public Dictionary<string, object> ReadTable()
         {
-            IDictionary<string, object> result = WireFormatting.ReadTable(_memory.Slice(_memoryOffset), out int bytesRead);
+            Dictionary<string, object> result = WireFormatting.ReadTable(_memory.Slice(_memoryOffset), out int bytesRead);
             _memoryOffset += bytesRead;
             return result;
         }
diff --git a/projects/RabbitMQ.Client/client/impl/MethodArgumentReader.cs b/projects/RabbitMQ.Client/client/impl/MethodArgumentReader.cs
index 6adcc34731..7c658ffcce 100644
--- a/projects/RabbitMQ.Client/client/impl/MethodArgumentReader.cs
+++ b/projects/RabbitMQ.Client/client/impl/MethodArgumentReader.cs
@@ -45,7 +45,7 @@
 
 namespace RabbitMQ.Client.Impl
 {
-    struct MethodArgumentReader
+    internal struct MethodArgumentReader
     {
         private int? _bit;
         private int _bits;
@@ -125,10 +125,10 @@ public string ReadShortstr()
             return result;
         }
 
-        public IDictionary<string, object> ReadTable()
+        public Dictionary<string, object> ReadTable()
         {
             ClearBits();
-            IDictionary<string, object> result = WireFormatting.ReadTable(_memory.Slice(_memoryOffset), out int bytesRead);
+            Dictionary<string, object> result = WireFormatting.ReadTable(_memory.Slice(_memoryOffset), out int bytesRead);
             _memoryOffset += bytesRead;
             return result;
         }
diff --git a/projects/RabbitMQ.Client/client/impl/ModelBase.cs b/projects/RabbitMQ.Client/client/impl/ModelBase.cs
index e17d4f482d..7e4fc95ded 100644
--- a/projects/RabbitMQ.Client/client/impl/ModelBase.cs
+++ b/projects/RabbitMQ.Client/client/impl/ModelBase.cs
@@ -55,12 +55,12 @@ namespace RabbitMQ.Client.Impl
 {
     abstract class ModelBase : IFullModel, IRecoverable
     {
-        public readonly IDictionary<string, IBasicConsumer> m_consumers = new Dictionary<string, IBasicConsumer>();
-
         ///<summary>Only used to kick-start a connection open
         ///sequence. See <see cref="Connection.Open"/> </summary>
         public BlockingCell<ConnectionStartDetails> m_connectionStartCell = null;
 
+        private readonly Dictionary<string, IBasicConsumer> _consumers = new Dictionary<string, IBasicConsumer>();
+
         private TimeSpan _handshakeContinuationTimeout = TimeSpan.FromSeconds(10);
         private TimeSpan _continuationTimeout = TimeSpan.FromSeconds(20);
 
@@ -500,11 +500,11 @@ public void OnSessionShutdown(object sender, ShutdownEventArgs reason)
             ConsumerDispatcher.Quiesce();
             SetCloseReason(reason);
             OnModelShutdown(reason);
-            BroadcastShutdownToConsumers(m_consumers, reason);
+            BroadcastShutdownToConsumers(_consumers, reason);
             ConsumerDispatcher.Shutdown(this).GetAwaiter().GetResult();;
         }
 
-        protected void BroadcastShutdownToConsumers(IDictionary<string, IBasicConsumer> cs, ShutdownEventArgs reason)
+        protected void BroadcastShutdownToConsumers(Dictionary<string, IBasicConsumer> cs, ShutdownEventArgs reason)
         {
             foreach (KeyValuePair<string, IBasicConsumer> c in cs)
             {
@@ -578,10 +578,10 @@ public void HandleBasicAck(ulong deliveryTag,
         public void HandleBasicCancel(string consumerTag, bool nowait)
         {
             IBasicConsumer consumer;
-            lock (m_consumers)
+            lock (_consumers)
             {
-                consumer = m_consumers[consumerTag];
-                m_consumers.Remove(consumerTag);
+                consumer = _consumers[consumerTag];
+                _consumers.Remove(consumerTag);
             }
             if (consumer == null)
             {
@@ -601,10 +601,10 @@ public void HandleBasicCancelOk(string consumerTag)
                             consumerTag
                             ));
             */
-            lock (m_consumers)
+            lock (_consumers)
             {
-                k.m_consumer = m_consumers[consumerTag];
-                m_consumers.Remove(consumerTag);
+                k.m_consumer = _consumers[consumerTag];
+                _consumers.Remove(consumerTag);
             }
             ConsumerDispatcher.HandleBasicCancelOk(k.m_consumer, consumerTag);
             k.HandleCommand(null); // release the continuation.
@@ -615,9 +615,9 @@ public void HandleBasicConsumeOk(string consumerTag)
             var k =
                 (BasicConsumerRpcContinuation)_continuationQueue.Next();
             k.m_consumerTag = consumerTag;
-            lock (m_consumers)
+            lock (_consumers)
             {
-                m_consumers[consumerTag] = k.m_consumer;
+                _consumers[consumerTag] = k.m_consumer;
             }
             ConsumerDispatcher.HandleBasicConsumeOk(k.m_consumer, consumerTag);
             k.HandleCommand(null); // release the continuation.
@@ -632,9 +632,9 @@ public virtual void HandleBasicDeliver(string consumerTag,
             ReadOnlyMemory<byte> body)
         {
             IBasicConsumer consumer;
-            lock (m_consumers)
+            lock (_consumers)
             {
-                consumer = m_consumers[consumerTag];
+                consumer = _consumers[consumerTag];
             }
             if (consumer == null)
             {
@@ -1005,9 +1005,9 @@ public void BasicCancel(string consumerTag)
                 k.GetReply(ContinuationTimeout);
             }
 
-            lock (m_consumers)
+            lock (_consumers)
             {
-                m_consumers.Remove(consumerTag);
+                _consumers.Remove(consumerTag);
             }
 
             ModelShutdown -= k.m_consumer.HandleModelShutdown;
@@ -1017,9 +1017,9 @@ public void BasicCancelNoWait(string consumerTag)
         {
             _Private_BasicCancel(consumerTag, true);
 
-            lock (m_consumers)
+            lock (_consumers)
             {
-                m_consumers.Remove(consumerTag);
+                _consumers.Remove(consumerTag);
             }
         }
 
diff --git a/projects/RabbitMQ.Client/client/impl/ProtocolBase.cs b/projects/RabbitMQ.Client/client/impl/ProtocolBase.cs
index be9788c72e..f4be4336aa 100644
--- a/projects/RabbitMQ.Client/client/impl/ProtocolBase.cs
+++ b/projects/RabbitMQ.Client/client/impl/ProtocolBase.cs
@@ -47,16 +47,19 @@ namespace RabbitMQ.Client.Framing.Impl
 {
     abstract class ProtocolBase : IProtocol
     {
-        public IDictionary<string, bool> Capabilities = new Dictionary<string, bool>();
+        public IDictionary<string, bool> Capabilities;
 
         public ProtocolBase()
         {
-            Capabilities["publisher_confirms"] = true;
-            Capabilities["exchange_exchange_bindings"] = true;
-            Capabilities["basic.nack"] = true;
-            Capabilities["consumer_cancel_notify"] = true;
-            Capabilities["connection.blocked"] = true;
-            Capabilities["authentication_failure_close"] = true;
+            Capabilities = new Dictionary<string, bool>
+            {
+                ["publisher_confirms"] = true,
+                ["exchange_exchange_bindings"] = true,
+                ["basic.nack"] = true,
+                ["consumer_cancel_notify"] = true,
+                ["connection.blocked"] = true,
+                ["authentication_failure_close"] = true
+            };
         }
 
         public abstract string ApiName { get; }
diff --git a/projects/RabbitMQ.Client/client/impl/Session.cs b/projects/RabbitMQ.Client/client/impl/Session.cs
index b448984ad7..474dffd54e 100644
--- a/projects/RabbitMQ.Client/client/impl/Session.cs
+++ b/projects/RabbitMQ.Client/client/impl/Session.cs
@@ -55,9 +55,10 @@ public Session(Connection connection, int channelNumber)
 
         public override void HandleFrame(in InboundFrame frame)
         {
-            using (Command cmd = _assembler.HandleFrame(in frame))
+            Command cmd = _assembler.HandleFrame(in frame);
+            if (cmd != null)
             {
-                if (cmd != null)
+                using (cmd)
                 {
                     OnCommandReceived(cmd);
                 }
diff --git a/projects/RabbitMQ.Client/client/impl/SessionManager.cs b/projects/RabbitMQ.Client/client/impl/SessionManager.cs
index 68963cfbd5..035d066998 100644
--- a/projects/RabbitMQ.Client/client/impl/SessionManager.cs
+++ b/projects/RabbitMQ.Client/client/impl/SessionManager.cs
@@ -55,7 +55,7 @@ class SessionManager
         public readonly ushort ChannelMax;
         private readonly IntAllocator _ints;
         private readonly Connection _connection;
-        private readonly IDictionary<int, ISession> _sessionMap = new Dictionary<int, ISession>();
+        private readonly Dictionary<int, ISession> _sessionMap = new Dictionary<int, ISession>();
         private bool _autoClose = false;
 
         public SessionManager(Connection connection, ushort channelMax)
diff --git a/projects/RabbitMQ.Client/client/impl/StreamProperties.cs b/projects/RabbitMQ.Client/client/impl/StreamProperties.cs
index 2821092b45..e97e4a53a9 100644
--- a/projects/RabbitMQ.Client/client/impl/StreamProperties.cs
+++ b/projects/RabbitMQ.Client/client/impl/StreamProperties.cs
@@ -55,11 +55,7 @@ public override object Clone()
             var clone = MemberwiseClone() as StreamProperties;
             if (IsHeadersPresent())
             {
-                clone.Headers = new Dictionary<string, object>();
-                foreach (KeyValuePair<string, object> entry in Headers)
-                {
-                    clone.Headers[entry.Key] = entry.Value;
-                }
+                clone.Headers = new Dictionary<string, object>(Headers);
             }
 
             return clone;
diff --git a/projects/RabbitMQ.Client/client/impl/WireFormatting.cs b/projects/RabbitMQ.Client/client/impl/WireFormatting.cs
index 1ade155571..6ae22715e5 100644
--- a/projects/RabbitMQ.Client/client/impl/WireFormatting.cs
+++ b/projects/RabbitMQ.Client/client/impl/WireFormatting.cs
@@ -49,7 +49,7 @@
 
 namespace RabbitMQ.Client.Impl
 {
-    class WireFormatting
+    internal class WireFormatting
     {
         public static decimal AmqpToDecimal(byte scale, uint unsignedMantissa)
         {
@@ -95,8 +95,8 @@ public static void DecimalToAmqp(decimal value, out byte scale, out int mantissa
 
         public static IList ReadArray(ReadOnlyMemory<byte> memory, out int bytesRead)
         {
-            IList array = new List<object>();
-            long arrayLength = NetworkOrderDeserializer.ReadUInt32(memory);
+            uint arrayLength = NetworkOrderDeserializer.ReadUInt32(memory);
+            List<object> array = new List<object>((int)arrayLength);
             bytesRead = 4;
             while (bytesRead - 4 < arrayLength)
             {
@@ -138,7 +138,7 @@ public static object ReadFieldValue(ReadOnlyMemory<byte> memory, out int bytesRe
                     bytesRead += 8;
                     return ReadTimestamp(slice);
                 case 'F':
-                    IDictionary<string, object> tableResult = ReadTable(slice, out int tableBytesRead);
+                    Dictionary<string, object> tableResult = ReadTable(slice, out int tableBytesRead);
                     bytesRead += tableBytesRead;
                     return tableResult;
                 case 'A':
@@ -207,10 +207,10 @@ public static string ReadShortstr(ReadOnlyMemory<byte> memory, out int bytesRead
         /// and F, as well as the QPid-0-8 specific b, d, f, l, s, t,
         /// x and V types and the AMQP 0-9-1 A type.
         ///</remarks>
-        /// <returns>A <seealso cref="System.Collections.Generic.IDictionary{TKey,TValue}"/>.</returns>
-        public static IDictionary<string, object> ReadTable(ReadOnlyMemory<byte> memory, out int bytesRead)
+        /// <returns>A <seealso cref="System.Collections.Generic.Dictionary{TKey,TValue}"/>.</returns>
+        public static Dictionary<string, object> ReadTable(ReadOnlyMemory<byte> memory, out int bytesRead)
         {
-            IDictionary<string, object> table = new Dictionary<string, object>();
+            Dictionary<string, object> table = new Dictionary<string, object>();
             long tableLength = NetworkOrderDeserializer.ReadUInt32(memory);
             bytesRead = 4;
             while ((bytesRead - 4) < tableLength)
@@ -247,9 +247,9 @@ public static int WriteArray(Memory<byte> memory, IList val)
             else
             {
                 int bytesWritten = 0;
-                foreach (object entry in val)
+                for (int index = 0; index < val.Count; index++)
                 {
-                    bytesWritten += WriteFieldValue(memory.Slice(4 + bytesWritten), entry); ;
+                    bytesWritten += WriteFieldValue(memory.Slice(4 + bytesWritten), val[index]);
                 }
 
                 NetworkOrderSerializer.WriteUInt32(memory, (uint)bytesWritten);
@@ -265,9 +265,9 @@ public static int GetArrayByteCount(IList val)
                 return byteCount;
             }
 
-            foreach (object entry in val)
+            for (int index = 0; index < val.Count; index++)
             {
-                byteCount += GetFieldValueByteCount(entry);
+                byteCount += GetFieldValueByteCount(val[index]);
             }
 
             return byteCount;
@@ -476,7 +476,7 @@ public static int WriteTable(Memory<byte> memory, IDictionary<string, object> va
                 int bytesWritten = 0;
                 foreach (KeyValuePair<string, object> entry in val)
                 {
-                    bytesWritten += WriteShortstr(slice.Slice(bytesWritten), entry.Key.ToString());
+                    bytesWritten += WriteShortstr(slice.Slice(bytesWritten), entry.Key);
                     bytesWritten += WriteFieldValue(slice.Slice(bytesWritten), entry.Value);
                 }
 
@@ -512,7 +512,7 @@ public static int GetTableByteCount(IDictionary<string, object> val)
 
             foreach (KeyValuePair<string, object> entry in val)
             {
-                byteCount += Encoding.UTF8.GetByteCount(entry.Key.ToString()) + 1;
+                byteCount += Encoding.UTF8.GetByteCount(entry.Key) + 1;
                 byteCount += GetFieldValueByteCount(entry.Value);
             }