Add add_binds to bulk binds processing for performance

Before with `prepared_statements: true`:

```
Warming up --------------------------------------
      where with ids     9.000  i/100ms
Calculating -------------------------------------
      where with ids     91.992  (± 7.6%) i/s -    459.000  in   5.020817s
```

Now with `prepared_statements: true`:

```
Warming up --------------------------------------
      where with ids    10.000  i/100ms
Calculating -------------------------------------
      where with ids     99.393  (± 8.0%) i/s -    500.000  in   5.069280s
```

activerecord/lib/active_record/statement_cache.rb

@@ -50,8 +50,13 @@ module ActiveRecord
 
       def sql_for(binds, connection)
         val = @values.dup
-        casted_binds = binds.map(&:value_for_database)
-        @indexes.each { |i| val[i] = connection.quote(casted_binds.shift) }
+        @indexes.each do |i|
+          value = binds.shift
+          if ActiveModel::Attribute === value
+            value = value.value_for_database
+          end
+          val[i] = connection.quote(value)
+        end
         val.join
       end
     end
@@ -75,6 +80,15 @@ module ActiveRecord
         self
       end
 
+      def add_binds(binds)
+        @binds.concat binds
+        binds.size.times do |i|
+          @parts << ", " unless i == 0
+          @parts << Substitute.new
+        end
+        self
+      end
+
       def value
         [@parts, @binds]
       end

activerecord/lib/arel/collectors/bind.rb

@@ -16,6 +16,11 @@ module Arel # :nodoc: all
         self
       end
 
+      def add_binds(binds)
+        @binds.concat binds
+        self
+      end
+
       def value
         @binds
       end

activerecord/lib/arel/collectors/composite.rb

@@ -22,6 +22,12 @@ module Arel # :nodoc: all
         self
       end
 
+      def add_binds(binds, &block)
+        left.add_binds(binds, &block)
+        right.add_binds(binds, &block)
+        self
+      end
+
       def value
         [left.value, right.value]
       end

activerecord/lib/arel/collectors/sql_string.rb

@@ -17,6 +17,11 @@ module Arel # :nodoc: all
         @bind_index += 1
         self
       end
+
+      def add_binds(binds, &block)
+        self << (@bind_index...@bind_index += binds.size).map(&block).join(", ")
+        self
+      end
     end
   end
 end

activerecord/lib/arel/collectors/substitute_binds.rb

@@ -20,6 +20,10 @@ module Arel # :nodoc: all
         self << quoter.quote(bind)
       end
 
+      def add_binds(binds)
+        self << binds.map { |bind| quoter.quote(bind) }.join(", ")
+      end
+
       def value
         delegate.value
       end

activerecord/lib/arel/visitors/postgresql.rb

@@ -41,10 +41,6 @@ module Arel # :nodoc: all
           visit(o.expr, collector) << " )"
         end
 
-        def visit_Arel_Nodes_BindParam(o, collector, value = o.value)
-          collector.add_bind(value) { |i| "$#{i}" }
-        end
-
         def visit_Arel_Nodes_GroupingElement(o, collector)
           collector << "( "
           visit(o.expr, collector) << " )"
@@ -92,6 +88,11 @@ module Arel # :nodoc: all
           collector << " NULLS LAST"
         end
 
+        BIND_BLOCK = proc { |i| "$#{i}" }
+        private_constant :BIND_BLOCK
+
+        def bind_block; BIND_BLOCK; end
+
         # Used by Lateral visitor to enclose select queries in parentheses
         def grouping_parentheses(o, collector)
           if o.expr.is_a? Nodes::SelectStatement

activerecord/lib/arel/visitors/to_sql.rb

@@ -336,13 +336,8 @@ module Arel # :nodoc: all
 
           if values.empty?
             collector << @connection.quote(nil)
-          elsif @connection.prepared_statements
-            values.each_with_index do |v, i|
-              collector << ", " unless i == 0
-              visit_Arel_Nodes_BindParam(nil, collector, v)
-            end
           else
-            collector << values.map! { |v| @connection.quote(v) }.join(", ")
+            collector.add_binds(values, &bind_block)
           end
 
           collector << ")"
@@ -695,8 +690,13 @@ module Arel # :nodoc: all
           collector << quote_table_name(join_name) << "." << quote_column_name(o.name)
         end
 
-        def visit_Arel_Nodes_BindParam(o, collector, value = o.value)
-          collector.add_bind(value) { "?" }
+        BIND_BLOCK = proc { "?" }
+        private_constant :BIND_BLOCK
+
+        def bind_block; BIND_BLOCK; end
+
+        def visit_Arel_Nodes_BindParam(o, collector)
+          collector.add_bind(o.value, &bind_block)
         end
 
         def visit_Arel_Nodes_SqlLiteral(o, collector)