https://github.com/AutoMapper/AutoMapper/pull/2350

MapAtRuntime.cs

static void Main(string[] args)
{
	int Count = 20;
	var sum = 0.0;
	for(int i=0;i<Count;i++){
		var config = new MapperConfiguration(cfg =>
		{
			cfg.CreateMap<Entity1, EntityDTO1>().ReverseMap();
			cfg.CreateMap<Entity2, EntityDTO2>().ReverseMap();
			cfg.CreateMap<Entity3, EntityDTO3>().ReverseMap();
			cfg.CreateMap<Entity4, EntityDTO4>().ReverseMap();
			cfg.CreateMap<Entity5, EntityDTO5>().ReverseMap();
			cfg.CreateMap<Entity6, EntityDTO6>().ReverseMap();
			cfg.CreateMap<Entity7, EntityDTO7>().ReverseMap();
			cfg.CreateMap<Entity8, EntityDTO8>().ReverseMap();
			cfg.CreateMap<Entity9, EntityDTO9>().ReverseMap();
			cfg.CreateMap<Entity10, EntityDTO10>().ReverseMap();
			cfg.CreateMap<Entity11, EntityDTO11>().ReverseMap();
			cfg.CreateMap<Entity12, EntityDTO12>().ReverseMap();
			cfg.CreateMap<Entity13, EntityDTO13>().ReverseMap();
			cfg.CreateMap<Entity14, EntityDTO14>().ReverseMap();
			cfg.CreateMap<Entity15, EntityDTO15>().ReverseMap();
			cfg.CreateMap<Entity16, EntityDTO16>().ReverseMap();
			cfg.CreateMap<Entity17, EntityDTO17>().ReverseMap();
			cfg.CreateMap<Entity18, EntityDTO18>().ReverseMap();
			cfg.CreateMap<Entity19, EntityDTO19>().ReverseMap();
			cfg.CreateMap<Entity20, EntityDTO20>().ReverseMap();
			cfg.CreateMap<Entity21, EntityDTO21>().ReverseMap();
			cfg.CreateMap<Entity22, EntityDTO22>().ReverseMap();
			cfg.CreateMap<Entity23, EntityDTO23>().ReverseMap();
			cfg.CreateMap<Entity24, EntityDTO24>().ReverseMap();
			cfg.CreateMap<Entity25, EntityDTO25>().ReverseMap();
			cfg.CreateMap<Entity26, EntityDTO26>().ReverseMap();
		});
		config.AssertConfigurationIsValid();
		var mapper = config.CreateMapper();	
	
		var list = new List<Entity1>();
		var initialize = new Initialize();
		list.Add(initialize.GenerateAppointment());
		var appointmentsDTO = mapper.Map<EntityDTO1>(list[0]);
		var timer = Stopwatch.StartNew();
		for(int i1=0;i1<100000;i1++){
			appointmentsDTO = mapper.Map<EntityDTO1>(list[0]);
		}
//		var list2 = new List<Entity1>();
//		var entity = new Entity1();
//		list2.Add(entity);
//		var DTOs = mapper.Map<EntityDTO1>(list2[0]);
//		var list3 = new List<Entity17>();
//		var entity17 = new Entity17();
//		list3.Add(entity17);
//		var DTOs17 = mapper.Map<EntityDTO17>(list3[0]);
//		var list4 = new List<Entity25>();
//		var entity25 = new Entity25();
//		list4.Add(entity25);
//		var DTOs25 = mapper.Map<EntityDTO25>(list4[0]);
		timer.Stop();
		Console.WriteLine(timer.Elapsed.TotalMilliseconds);
		sum+=timer.Elapsed.TotalMilliseconds;
		GC.Collect();
	}
	Console.WriteLine("Average "+sum/Count);
}

public class Initialize
{
  Entity2 appointmentStatusHistory1;
  Entity8 center1;
  Entity12 insurance1;
  Entity14 patient1;
  Entity17 resource1;
  Entity20 service1;
  Entity22 speciality1;

  public Initialize()
  {
      appointmentStatusHistory1 = new Entity2 { Id = Guid.NewGuid() };
      center1 = new Entity8 { Id = Guid.NewGuid() };
      insurance1 = new Entity12 { Id = Guid.NewGuid() };
      patient1 = new Entity14 { Id = Guid.NewGuid() };
      resource1 = new Entity17 { Id = Guid.NewGuid() };
      service1 = new Entity20 { Id = Guid.NewGuid() };
      speciality1 = new Entity22 { Id = Guid.NewGuid() };

      service1.Entity22 = speciality1;
      service1.Entity22Id = speciality1.Id;
  }

  public Entity1 GenerateAppointment()
  {
      var appointment1 = new Entity1 { Id = Guid.NewGuid() };
      appointmentStatusHistory1.Entity1 = appointment1;
      appointmentStatusHistory1.Entity1Id = appointment1.Id;
      appointment1.Entity8 = center1;
      appointment1.Entity8Id = center1.Id;
      appointment1.Entity12 = insurance1;
      appointment1.Entity12Id = insurance1.Id;
      appointment1.Entity14 = patient1;
      appointment1.Entity14Id = patient1.Id;
      appointment1.Entity17 = resource1;
      appointment1.Entity17Id = resource1.Id;
      appointment1.Entity20 = service1;
      appointment1.Entity20Id = service1.Id;
      appointment1.Entity22 = speciality1;
      appointment1.Entity22Id = speciality1.Id;
      return appointment1;
  }
}

public class BaseEntity
{
   public Guid Id { get; set; }
}

public class Entity1 : BaseEntity
{
   public Entity1()
   {
       this.Entities2 = new Entity2();
   }
   public Guid Entity17Id { get; set; }
   public Entity17 Entity17 { get; set; }
   public Guid? Entity22Id { get; set; }
   public Entity22 Entity22 { get; set; }
   public Guid? Entity20Id { get; set; }
   public Entity20 Entity20 { get; set; }
   public Guid? Entity12Id { get; set; }
   public Entity12 Entity12 { get; set; }
   public Guid Entity14Id { get; set; }
   public Entity14 Entity14 { get; set; }
   public Guid Entity8Id { get; set; }
   public Entity8 Entity8 { get; set; }
   public Entity2 Entities2 { get; set; }
}



public class Entity10 : BaseEntity
{
   public Entity10()
   {
       this.Entities11 = new Entity11();
   }
   public Entity11 Entities11 { get; set; }
}

public class Entity11 : BaseEntity
{
   public Entity11()
   {
       this.Entities10 = new Entity10();
       this.Entities8 = new Entity8();
   }
   public Entity10 Entities10 { get; set; }
   public Entity8 Entities8 { get; set; }
}

public class Entity12 : BaseEntity
{
   public Entity12()
   {
       //this.Entities20 = new Entity20();
       //this.Entities14 = new Entity14();
       //this.Entities16 = new Entity16();
   }
   public Entity20 Entities20 { get; set; }
   public Entity16 Entities16 { get; set; }
   public Entity14 Entities14 { get; set; }
}

public class Entity13 : BaseEntity
{
   public Guid Entity17Id { get; set; }
   public Entity17 Entity17 { get; set; }
   public Guid Entity8Id { get; set; }
   public Entity8 Entity8 { get; set; }
}

public class Entity14 : BaseEntity
{
   public Entity14()
   {
       this.Entities12 = new Entity12();
       this.Entities1 = new Entity1();
   }

   public Entity12 Entities12 { get; set; }
   public Entity1 Entities1 { get; set; }
}

public class Entity15 : BaseEntity
{
   public Guid Entity17Id { get; set; }
   public Entity17 Entity17 { get; set; }
}

public class Entity16 : BaseEntity
{
   public Guid Entity20Id { get; set; }
   public Entity20 Entity20 { get; set; }
   public Guid Entity12Id { get; set; }
   public Entity12 Entity12 { get; set; }
}

public class Entity17 :BaseEntity
{
   public Entity17()
   {
       //this.Entities20 = new Entity20();
       this.Entities8 = new Entity8();
       this.Entities5 = new Entity5();
       this.Entities18 = new Entity18();
   }

   public Entity20 Entities20 { get; set; }
   public Entity8 Entities8 { get; set; }
   public Entity5 Entities5 { get; set; }
   public Entity18 Entities18 { get; set; }
}

public class Entity18 : BaseEntity
{
   public Guid Entity17Id { get; set; }
   public Entity17 Entity17 { get; set; }
   public Guid Entity20Id { get; set; }
   public Entity20 Entity20 { get; set; }
}

public class Entity19 : BaseEntity
{
   public Guid Entity25Id { get; set; }
   public Entity25 Entity25 { get; set; }
}

public class Entity2 : BaseEntity
{
   public Guid Entity1Id { get; set; }
   public Entity1 Entity1 { get; set; }
}

public class Entity20 : BaseEntity
{
   public Entity20()
   {
       //this.Entities8 = new Entity8();
       //this.Entities26 = new Entity26();
       //this.Entities12 = new Entity12();
       //this.Entities17 = new Entity17();
       //this.Entities21 = new Entity21();
       //this.Entities16 = new Entity16();
   }

   public Guid Entity3Id { get; set; }
   public Entity3 Entity3 { get; set; }
   public Guid Entity22Id { get; set; }
   public Entity22 Entity22 { get; set; }
   public Entity8 Entities8 { get; set; }
   public Entity26 Entities26 { get; set; }
   public Entity12 Entities12 { get; set; }
   public Entity17 Entities17 { get; set; }
   public Entity21 Entities21 { get; set; }
   public Entity16 Entities16 { get; set; }
}

public class Entity21 : BaseEntity
{
   public Guid Entity20Id { get; set; }
   public Entity20 Entity20 { get; set; }
}

public class Entity22 : BaseEntity
{
   public Entity22()
   {
       this.Entities20 = new Entity20();
       this.Entities24 = new Entity24();
   }
   public Entity20 Entities20 { get; set; }
   public Entity24 Entities24 { get; set; }
}

public class Entity23 : BaseEntity
{
   public Guid Entity5Id { get; set; }
   public Entity5 Entity5 { get; set; }
}

public class Entity24 : BaseEntity
{
   public Guid Entity3Id { get; set; }
   public Entity3 Entity3 { get; set; }
   public Guid Entity22Id { get; set; }
   public Entity22 Entity22 { get; set; }
}

public class Entity25 : BaseEntity
{
   public Entity25()
   {
       this.Entities19 = new Entity19();
   }

   public Entity19 Entities19 { get; set; }
   public Guid? Entity8Id { get; set; }
   public Entity8 Entity8 { get; set; }
   public Guid? Entity17Id { get; set; }
   public Entity17 Entity17 { get; set; }
}

public class Entity26 : BaseEntity
{
   public Entity26()
   {
       //this.Entities20 = new Entity20();
   }

   public Entity20 Entities20 { get; set; }
}

public class Entity3 : BaseEntity
{
   public Entity3()
   {
       this.Entities4 = new Entity4();
       this.Entities8 = new Entity8();
   }
   public Entity4 Entities4 { get; set; }
   public Entity8 Entities8 { get; set; }
}

public class Entity4 : BaseEntity
{
   public Guid Entity3Id { get; set; }
   public Entity3 Entity3 { get; set; }
}

public class Entity5 : BaseEntity
{
   public Entity5()
   {
       //this.Entities6 = new Entity6();
       //this.TimeSlots = new Entity23();
       //this.Entities5 = new Entity5();
   }

   public Guid? Entity8Id { get; set; }
   public Entity8 Entity8 { get; set; }
   public Guid? Entity17Id { get; set; }
   public Entity17 Entity17 { get; set; }
   public Guid? Entity5Id { get; set; }
   public Entity5 Entity5Exception { get; set; }
   public Entity5 Entities5 { get; set; }
   public Entity6 Entities6 { get; set; }
   public Entity23 TimeSlots { get; set; }
}

public class Entity6 : BaseEntity
{
   public Entity6()
   {
       this.Entities12 = new Entity12();
   }

   public Guid Entity5Id { get; set; }
   public Entity5 Entity5 { get; set; }
   public Guid Entity20Id { get; set; }
   public Entity20 Entity20 { get; set; }
   public Entity12 Entities12 { get; set; }
}

public class Entity7 : BaseEntity
{
   public Guid Entity25Id { get; set; }
   public Entity25 Entity25 { get; set; }
   public Guid? Entity14Id { get; set; }
   public Entity14 Entity14 { get; set; }
}

public class Entity8 : BaseEntity
{
   public Entity8()
   {
       //this.Entities20 = new Entity20();
       //this.Entities22 = new Entity22();
       //this.Entities3 = new Entity3();
       //this.Entities11 = new Entity11();
       //this.Entities17 = new Entity17();
   }

   public Entity20 Entities20 { get; set; }
   public Entity17 Entities17 { get; set; }
   public Entity22 Entities22 { get; set; }
   public Entity3 Entities3 { get; set; }
   public Entity11 Entities11 { get; set; }
}

public class Entity9 : BaseEntity
{
   public Guid Entity3Id { get; set; }
   public Entity3 Entity3 { get; set; }
}

public class EntityDTO1 : BaseEntity
{
   public EntityDTO1()
   {
       this.Entities2 = new EntityDTO2();
   }
   public Guid Entity17Id { get; set; }
   public EntityDTO17 Entity17 { get; set; }
   public Guid? Entity22Id { get; set; }
   public EntityDTO22 Entity22 { get; set; }
   public Guid? Entity20Id { get; set; }
   public EntityDTO20 Entity20 { get; set; }
   public Guid? Entity12Id { get; set; }
   public EntityDTO12 Entity12 { get; set; }
   public Guid Entity14Id { get; set; }
   public EntityDTO14 Entity14 { get; set; }
   public Guid Entity8Id { get; set; }
   public EntityDTO8 Entity8 { get; set; }
   public EntityDTO2 Entities2 { get; set; }
}

public class EntityDTO10 : BaseEntity
{
   public EntityDTO10()
   {
       this.Entities11 = new EntityDTO11();
   }
   public EntityDTO11 Entities11 { get; set; }
}

public class EntityDTO11 : BaseEntity
{
   public EntityDTO11()
   {
       //this.Entities10 = new EntityDTO10();
       //this.Entities8 = new EntityDTO8();
   }
   public EntityDTO10 Entities10 { get; set; }
   public EntityDTO8 Entities8 { get; set; }
}

public class EntityDTO12 : BaseEntity
{
   public EntityDTO12()
   {
       //this.Entities20 = new EntityDTO20();
       //this.Entities14 = new EntityDTO14();
       //Entities16 = new EntityDTO16();
   }
   public EntityDTO20 Entities20 { get; set; }
   public EntityDTO16 Entities16 { get; set; }
   public EntityDTO14 Entities14 { get; set; }
}

public class EntityDTO13 : BaseEntity
{
   public Guid Entity17Id { get; set; }
   public EntityDTO17 Entity17 { get; set; }
   public Guid Entity8Id { get; set; }
   public EntityDTO8 Entity8 { get; set; }
}

public class EntityDTO14 : BaseEntity
{
   public EntityDTO14()
   {
       this.Entities12 = new EntityDTO12();
       this.Entities1 = new EntityDTO1();
   }

   //public Address Address { get; set; }
   public EntityDTO12 Entities12 { get; set; }
   public EntityDTO1 Entities1 { get; set; }
}

public class EntityDTO15 : BaseEntity
{
   public EntityDTO15()
   {
   }
   public Guid Entity17Id { get; set; }
   public EntityDTO17 Entity17 { get; set; }
}

public class EntityDTO16 : BaseEntity
{
   public Guid Entity20Id { get; set; }
   public EntityDTO20 Entity20 { get; set; }
   public Guid Entity12Id { get; set; }
   public EntityDTO12 Entity12 { get; set; }
}

public class EntityDTO17 :BaseEntity
{
   public EntityDTO17()
   {
       //this.Entities20 = new EntityDTO20();
       //this.Entities8 = new EntityDTO8();
       //this.Entities5 = new EntityDTO5();
       //this.Entities18 = new EntityDTO18();
   }

   public EntityDTO20 Entities20 { get; set; }
   public EntityDTO8 Entities8 { get; set; }
   public EntityDTO5 Entities5 { get; set; }
   public EntityDTO18 Entities18 { get; set; }
}

public class EntityDTO18 : BaseEntity
{
   public Guid Entity17Id { get; set; }
   public EntityDTO17 Entity17 { get; set; }
   public Guid Entity20Id { get; set; }
   public EntityDTO20 Entity20 { get; set; }
}

public class EntityDTO19 : BaseEntity
{
   public Guid Entity25Id { get; set; }
   public EntityDTO25 Entity25 { get; set; }
}

public class EntityDTO2 : BaseEntity
{
   public Guid Entity1Id { get; set; }
   public EntityDTO1 Entity1 { get; set; }
}

public class EntityDTO20 : BaseEntity
{
   //TODO Remove comments
   public EntityDTO20()
   {
       //this.Entities8 = new EntityDTO8();
       //this.Entities26 = new EntityDTO26();
       //this.Entities12 = new EntityDTO12();
       //this.Entities17 = new EntityDTO17();
       //this.Entities21 = new EntityDTO21();
       //this.Entities16 = new EntityDTO16();
   }

   public Guid Entity3Id { get; set; }
   public EntityDTO3 Entity3 { get; set; }
   public Guid Entity22Id { get; set; }
   public EntityDTO22 Entity22 { get; set; }
   public EntityDTO8 Entities8 { get; set; }
   public EntityDTO26 Entities26 { get; set; }
   public EntityDTO12 Entities12 { get; set; }
   public EntityDTO17 Entities17 { get; set; }
   public EntityDTO21 Entities21 { get; set; }
   public EntityDTO16 Entities16 { get; set; }
}

public class EntityDTO21 : BaseEntity
{
   public Guid Entity20Id { get; set; }
   public EntityDTO20 Entity20 { get; set; }
}

public class EntityDTO22 : BaseEntity
{
   public EntityDTO22()
   {
       //this.Entities20 = new EntityDTO20();
       //this.Entities24 = new EntityDTO24();
   }
   public EntityDTO20 Entities20 { get; set; }
   public EntityDTO24 Entities24 { get; set; }
}

public class EntityDTO23 : BaseEntity
{
   public Guid Entity5Id { get; set; }
   public EntityDTO5 Entity5 { get; set; }
}

public class EntityDTO24 : BaseEntity
{
   public Guid Entity3Id { get; set; }
   public EntityDTO3 Entity3 { get; set; }
   public Guid Entity22Id { get; set; }
   public EntityDTO22 Entity22 { get; set; }
}

public class EntityDTO25 : BaseEntity
{
   public EntityDTO25()
   {
       this.Entities19 = new EntityDTO19();
   }

   public EntityDTO19 Entities19 { get; set; }
   public Guid? Entity8Id { get; set; }
   public EntityDTO8 Entity8 { get; set; }
   public Guid? Entity17Id { get; set; }
   public EntityDTO17 Entity17 { get; set; }
}

public class EntityDTO26 : BaseEntity
{
   public EntityDTO26()
   {
       this.Entities20 = new EntityDTO20();
   }

   public EntityDTO20 Entities20 { get; set; }
}

public class EntityDTO3 : BaseEntity
{
   public EntityDTO3()
   {
       //this.Entities4 = new EntityDTO4();
       //this.Entities8 = new EntityDTO8();
   }
   public EntityDTO4 Entities4 { get; set; }
   public EntityDTO8 Entities8 { get; set; }
}

public class EntityDTO4 : BaseEntity
{
   public Guid Entity3Id { get; set; }
   public EntityDTO3 Entity3 { get; set; }
}

public class EntityDTO5 : BaseEntity
{
   public EntityDTO5()
   {
       //this.Entities6 = new EntityDTO6();
       //this.TimeSlots = new EntityDTO23();
       //this.Entities5 = new EntityDTO5();
   }

   public Guid? Entity8Id { get; set; }
   public EntityDTO8 Entity8 { get; set; }
   public Guid? Entity17Id { get; set; }
   public EntityDTO17 Entity17 { get; set; }
   public Guid? Entity5Id { get; set; }
   public EntityDTO5 Entity5Exception { get; set; }
   public EntityDTO5 Entities5 { get; set; }
   public EntityDTO6 Entities6 { get; set; }
   public EntityDTO23 TimeSlots { get; set; }
}

public class EntityDTO6 : BaseEntity
{
   public EntityDTO6()
   {
       //this.Entities12 = new EntityDTO12();
   }

   public Guid Entity5Id { get; set; }
   public EntityDTO5 Entity5 { get; set; }
   public Guid Entity20Id { get; set; }
   public EntityDTO20 Entity20 { get; set; }
   public EntityDTO12 Entities12 { get; set; }
}

public class EntityDTO7 : BaseEntity
{
   public Guid Entity25Id { get; set; }
   public EntityDTO25 Entity25 { get; set; }
   public Guid? Entity14Id { get; set; }
   public EntityDTO14 Entity14 { get; set; }
}

public class EntityDTO8 : BaseEntity
{
   public EntityDTO8()
   {
       this.Entities20 = new EntityDTO20();
       this.Entities22 = new EntityDTO22();
       this.Entities3 = new EntityDTO3();
       this.Entities11 = new EntityDTO11();
       this.Entities17 = new EntityDTO17();
   }

   public EntityDTO20 Entities20 { get; set; }
   public EntityDTO17 Entities17 { get; set; }
   public EntityDTO22 Entities22 { get; set; }
   public EntityDTO3 Entities3 { get; set; }
   public EntityDTO11 Entities11 { get; set; }
}

public class EntityDTO9 : BaseEntity
{
   public Guid Entity3Id { get; set; }
   public EntityDTO3 Entity3 { get; set; }
}