diff --git a/lib/protobuf/field/base_field.rb b/lib/protobuf/field/base_field.rb
index 3ae505a4..f2b8426a 100644
--- a/lib/protobuf/field/base_field.rb
+++ b/lib/protobuf/field/base_field.rb
@@ -176,16 +176,18 @@ def define_accessor
         else
           define_getter
           define_setter
+          define_decode_setter
         end
       end
 
       def define_array_getter
         field = self
+        field_name = field.name
         method_name = field.getter
 
         message_class.class_eval do
           define_method(method_name) do
-            @values[field.name] ||= ::Protobuf::Field::FieldArray.new(field)
+            @values[field_name] ||= ::Protobuf::Field::FieldArray.new(field)
           end
         end
 
@@ -194,6 +196,7 @@ def define_array_getter
 
       def define_array_setter
         field = self
+        field_name = field.name
         method_name = field.setter
 
         message_class.class_eval do
@@ -205,15 +208,15 @@ def define_array_setter
             else
               fail TypeError, <<-TYPE_ERROR
                 Expected repeated value of type '#{field.type_class}'
-                Got '#{val.class}' for repeated protobuf field #{field.name}
+                Got '#{val.class}' for repeated protobuf field #{field_name}
               TYPE_ERROR
             end
 
             if val.nil? || (val.respond_to?(:empty?) && val.empty?)
-              @values.delete(field.name)
+              @values.delete(field_name)
             else
-              @values[field.name] ||= ::Protobuf::Field::FieldArray.new(field)
-              @values[field.name].replace(val)
+              @values[field_name] ||= ::Protobuf::Field::FieldArray.new(field)
+              @values[field_name].replace(val)
             end
           end
         end
@@ -234,17 +237,22 @@ def define_getter
         ::Protobuf.field_deprecator.deprecate_method(message_class, method_name) if field.deprecated?
       end
 
+      def define_decode_setter
+        # empty for now
+      end
+
       def define_setter
         field = self
+        field_name = field.name
         method_name = field.setter
 
         message_class.class_eval do
           define_method(method_name) do |val|
             @encode = nil
             if val.nil? || (val.respond_to?(:empty?) && val.empty?)
-              @values.delete(field.name)
+              @values.delete(field_name)
             elsif field.acceptable?(val)
-              @values[field.name] = field.coerce!(val)
+              @values[field_name] = field.coerce!(val)
             else
               fail TypeError, "Unacceptable value #{val} for field #{field.name} of type #{field.type_class}"
             end
diff --git a/lib/protobuf/field/bool_field.rb b/lib/protobuf/field/bool_field.rb
index afe6c112..4422d93e 100644
--- a/lib/protobuf/field/bool_field.rb
+++ b/lib/protobuf/field/bool_field.rb
@@ -35,6 +35,19 @@ def decode(value)
         value == 1
       end
 
+      def define_decode_setter
+        field = self
+        field_name = field.name
+        tag_method_name = "_protobuf_decode_setter_#{field.tag}"
+
+        message_class.class_eval do
+          define_method(tag_method_name) do |val|
+            @encode = nil
+            @values[field_name] = field.decode(val)
+          end
+        end
+      end
+
       def encode(value)
         [value ? 1 : 0].pack('C')
       end
diff --git a/lib/protobuf/field/bytes_field.rb b/lib/protobuf/field/bytes_field.rb
index d7f4aee4..7c61a136 100644
--- a/lib/protobuf/field/bytes_field.rb
+++ b/lib/protobuf/field/bytes_field.rb
@@ -56,8 +56,23 @@ def wire_type
       # Private Instance Methods
       #
 
+      def define_decode_setter
+        field = self
+        field_name = field.name
+        tag_method_name = "_protobuf_decode_setter_#{field.tag}"
+
+        message_class.class_eval do
+          define_method(tag_method_name) do |val|
+            @encode = nil
+            @values[field_name] = field.decode(val)
+          end
+        end
+      end
+
       def define_setter
         field = self
+        field_name = field.name
+        field_type_class = field.type_class
         method_name = field.setter
 
         message_class.class_eval do
@@ -65,13 +80,13 @@ def define_setter
             @encode = nil
             case val
             when String, Symbol
-              @values[field.name] = "#{val}"
+              @values[field_name] = "#{val}"
             when NilClass
-              @values.delete(field.name)
+              @values.delete(field_name)
             when ::Protobuf::Message
-              @values[field.name] = val.dup
+              @values[field_name] = val.dup
             else
-              fail TypeError, "Unacceptable value #{val} for field #{field.name} of type #{field.type_class}"
+              fail TypeError, "Unacceptable value #{val} for field #{field_name} of type #{field_type_class}"
             end
           end
         end
diff --git a/lib/protobuf/field/enum_field.rb b/lib/protobuf/field/enum_field.rb
index 71632cde..96e13e9e 100644
--- a/lib/protobuf/field/enum_field.rb
+++ b/lib/protobuf/field/enum_field.rb
@@ -38,19 +38,36 @@ def enum?
       # Private Instance Methods
       #
 
+      def define_decode_setter
+        field = self
+        field_name = field.name
+        field_type_class = field.type_class
+        tag_method_name = "_protobuf_decode_setter_#{field.tag}"
+
+        message_class.class_eval do
+          define_method(tag_method_name) do |val|
+            @encode = nil
+            @values[field_name] = field_type_class.fetch(val)
+          end
+        end
+      end
+
       def define_setter
         field = self
+        field_name = field.name
+        field_type_class = field.type_class
+
         message_class.class_eval do
-          define_method("#{field.name}=") do |value|
+          define_method("#{field_name}=") do |value|
             @encode = nil
             orig_value = value
             if value.nil?
-              @values.delete(field.name)
+              @values.delete(field_name)
             else
-              value = field.type_class.fetch(value)
+              value = field_type_class.fetch(value)
               fail TypeError, "Invalid Enum value: #{orig_value.inspect} for #{field.name}" unless value
 
-              @values[field.name] = value
+              @values[field_name] = value
             end
           end
         end
diff --git a/lib/protobuf/field/integer_field.rb b/lib/protobuf/field/integer_field.rb
index 5eb3b064..254a2a9d 100644
--- a/lib/protobuf/field/integer_field.rb
+++ b/lib/protobuf/field/integer_field.rb
@@ -9,10 +9,23 @@ class IntegerField < VarintField
       #
 
       def decode(value)
-        value -= 0x1_0000_0000_0000_0000 if (value & 0x8000_0000_0000_0000).nonzero?
+        value -= 0x1_0000_0000_0000_0000 if (value & 0x8000_0000_0000_0000) != 0
         value
       end
 
+      def define_decode_setter
+        field = self
+        field_name = field.name
+        tag_method_name = "_protobuf_decode_setter_#{field.tag}"
+
+        message_class.class_eval do
+          define_method(tag_method_name) do |val|
+            @encode = nil
+            @values[field_name] = field.decode(val)
+          end
+        end
+      end
+
       def encode(value)
         # original Google's library uses 64bits integer for negative value
         ::Protobuf::Field::VarintField.encode(value & 0xffff_ffff_ffff_ffff)
diff --git a/lib/protobuf/field/message_field.rb b/lib/protobuf/field/message_field.rb
index 8cb37bd7..c24f8104 100644
--- a/lib/protobuf/field/message_field.rb
+++ b/lib/protobuf/field/message_field.rb
@@ -17,9 +17,7 @@ def decode(bytes)
       end
 
       def encode(value)
-        bytes = value.encode
-        result = ::Protobuf::Field::VarintField.encode(bytes.size)
-        result << bytes
+        "#{::Protobuf::Field::VarintField.encode(value.encode.size)}#{value.encode}"
       end
 
       def message?
@@ -38,20 +36,23 @@ def wire_type
 
       def define_setter
         field = self
+        field_name = field.name
+        field_type_class = field.type_class
+
         message_class.class_eval do
-          define_method("#{field.name}=") do |val|
+          define_method("#{field_name}=") do |val|
             @encode = nil
             case
             when val.nil?
-              @values.delete(field.name)
-            when val.is_a?(field.type_class)
-              @values[field.name] = val
+              @values.delete(field_name)
+            when val.is_a?(field_type_class)
+              @values[field_name] = val
             when val.respond_to?(:to_proto)
-              @values[field.name] = val.to_proto
+              @values[field_name] = val.to_proto
             when val.respond_to?(:to_hash)
-              @values[field.name] = field.type_class.new(val.to_hash)
+              @values[field_name] = field_type_class.new(val.to_hash)
             else
-              fail TypeError, "Expected value of type '#{field.type_class}' for field #{field.name}, but got '#{val.class}'"
+              fail TypeError, "Expected value of type '#{field_type_class}' for field #{field_name}, but got '#{val.class}'"
             end
           end
         end
diff --git a/lib/protobuf/field/sfixed32_field.rb b/lib/protobuf/field/sfixed32_field.rb
index 9f9b64e9..c8ca1f3a 100644
--- a/lib/protobuf/field/sfixed32_field.rb
+++ b/lib/protobuf/field/sfixed32_field.rb
@@ -10,7 +10,7 @@ class Sfixed32Field < Int32Field
 
       def decode(bytes)
         value  = bytes.unpack('V').first
-        value -= 0x1_0000_0000 if (value & 0x8000_0000).nonzero?
+        value -= 0x1_0000_0000 if (value & 0x8000_0000) != 0
         value
       end
 
diff --git a/lib/protobuf/field/sfixed64_field.rb b/lib/protobuf/field/sfixed64_field.rb
index fc296483..d7ab755e 100644
--- a/lib/protobuf/field/sfixed64_field.rb
+++ b/lib/protobuf/field/sfixed64_field.rb
@@ -11,7 +11,7 @@ class Sfixed64Field < Int64Field
       def decode(bytes)
         values = bytes.unpack('VV') # 'Q' is machine-dependent, don't use
         value  = values[0] + (values[1] << 32)
-        value -= 0x1_0000_0000_0000_0000 if (value & 0x8000_0000_0000_0000).nonzero?
+        value -= 0x1_0000_0000_0000_0000 if (value & 0x8000_0000_0000_0000) != 0
         value
       end
 
diff --git a/lib/protobuf/field/signed_integer_field.rb b/lib/protobuf/field/signed_integer_field.rb
index 8945f771..44f5730c 100644
--- a/lib/protobuf/field/signed_integer_field.rb
+++ b/lib/protobuf/field/signed_integer_field.rb
@@ -16,6 +16,19 @@ def decode(value)
         end
       end
 
+      def define_decode_setter
+        field = self
+        field_name = field.name
+        tag_method_name = "_protobuf_decode_setter_#{field.tag}"
+
+        message_class.class_eval do
+          define_method(tag_method_name) do |val|
+            @encode = nil
+            @values[field_name] = field.decode(val)
+          end
+        end
+      end
+
       def encode(value)
         if value >= 0
           VarintField.encode(value << 1)
diff --git a/lib/protobuf/field/string_field.rb b/lib/protobuf/field/string_field.rb
index ac36ea70..5050daba 100644
--- a/lib/protobuf/field/string_field.rb
+++ b/lib/protobuf/field/string_field.rb
@@ -20,6 +20,20 @@ def decode(bytes)
         bytes_to_decode
       end
 
+      def define_decode_setter
+        field = self
+        field_name = field.name
+        tag_method_name = "_protobuf_decode_setter_#{field.tag}"
+
+        message_class.class_eval do
+          define_method(tag_method_name) do |val|
+            @encode = nil
+            val.force_encoding(::Protobuf::Field::StringField::ENCODING)
+            @values[field_name] = val
+          end
+        end
+      end
+
       def encode(value)
         value_to_encode = value.dup
         value_to_encode.encode!(::Protobuf::Field::StringField::ENCODING, :invalid => :replace, :undef => :replace, :replace => "")
diff --git a/lib/protobuf/field/varint_field.rb b/lib/protobuf/field/varint_field.rb
index 59fabdcb..9b5ba415 100644
--- a/lib/protobuf/field/varint_field.rb
+++ b/lib/protobuf/field/varint_field.rb
@@ -52,6 +52,7 @@ def self.encode(value, use_cache = true)
       #
 
       def acceptable?(val)
+        return true if val.is_a?(Integer) && val >= 0 && val < INT32_MAX
         int_val = coerce!(val)
         int_val >= self.class.min && int_val <= self.class.max
       rescue
@@ -63,6 +64,19 @@ def coerce!(val)
         Integer(val, 10)
       end
 
+      def define_decode_setter
+        field = self
+        field_name = field.name
+        tag_method_name = "_protobuf_decode_setter_#{field.tag}"
+
+        message_class.class_eval do
+          define_method(tag_method_name) do |val|
+            @encode = nil
+            @values[field_name] = val
+          end
+        end
+      end
+
       def decode(value)
         value
       end
diff --git a/lib/protobuf/message.rb b/lib/protobuf/message.rb
index 9ac1332e..944fc8c4 100644
--- a/lib/protobuf/message.rb
+++ b/lib/protobuf/message.rb
@@ -77,14 +77,13 @@ def each_field
       return to_enum(:each_field) unless block_given?
 
       self.class.all_fields.each do |field|
-        value = __send__(field.getter)
-        yield(field, value)
+        yield(field, __send__(field.getter))
       end
     end
 
     def each_field_for_serialization
       self.class.all_fields.each do |field|
-        value = @values[field.getter]
+        value = @values[field.name]
         if value.nil?
           fail ::Protobuf::SerializationError, "Required field #{self.class.name}##{field.name} does not have a value." if field.required?
           next
@@ -146,18 +145,16 @@ def ==(other)
     end
 
     def [](name)
-      if (field = self.class.get_field(name, true))
-        __send__(field.getter)
-      end
+      __send__(name) if respond_to?(name)
     end
 
     def []=(name, value)
-      if (field = self.class.get_field(name, true))
-        __send__(field.setter, value) unless value.nil?
+      setter = "#{name}="
+
+      if respond_to?(setter)
+        __send__(setter, value) unless value.nil?
       else
-        unless ::Protobuf.ignore_unknown_fields?
-          fail ::Protobuf::FieldNotDefinedError, name
-        end
+        fail ::Protobuf::FieldNotDefinedError, name unless ::Protobuf.ignore_unknown_fields?
       end
     end
 
diff --git a/lib/protobuf/message/serialization.rb b/lib/protobuf/message/serialization.rb
index 668b6cea..68670bc0 100644
--- a/lib/protobuf/message/serialization.rb
+++ b/lib/protobuf/message/serialization.rb
@@ -78,6 +78,9 @@ def encode_to(stream)
       private
 
       def set_field_bytes(tag, bytes)
+        tag_setter_name = "_protobuf_decode_setter_#{tag}"
+        return __send__(tag_setter_name, bytes) if respond_to?(tag_setter_name)
+
         field = self.class.get_field(tag, true)
         field.set(self, bytes) if field
       end
diff --git a/lib/protobuf/varint_pure.rb b/lib/protobuf/varint_pure.rb
index eeffbecc..6fe38aad 100644
--- a/lib/protobuf/varint_pure.rb
+++ b/lib/protobuf/varint_pure.rb
@@ -1,12 +1,12 @@
 module Protobuf
   module VarintPure
     def decode(stream)
-      value = index = 0
+      value = shift = 0
       begin
         byte = stream.readbyte
-        value |= (byte & 0x7f) << (7 * index)
-        index += 1
-      end while (byte & 0x80).nonzero?
+        value |= (byte & 127) << shift
+        shift += 7
+      end while byte > 127
       value
     end
   end
diff --git a/spec/benchmark/tasks.rb b/spec/benchmark/tasks.rb
index 631439d6..a98b9683 100644
--- a/spec/benchmark/tasks.rb
+++ b/spec/benchmark/tasks.rb
@@ -119,7 +119,7 @@ def profile_code(output, &block)
     when :jruby
       profile_data = JRuby::Profiler.profile(&block)
       File.open(output, 'w') do |f|
-        JRuby::Profiler::FlatProfilePrinter.new(profile_data).printProfile(f)
+        JRuby::Profiler::GraphProfilePrinter.new(profile_data).printProfile(f)
       end
     end
   end