我有一个Save对象，它有几个关联的集合。对象的总大小如下：

对象之间的关系可以从这个Map中推断出来，并且看起来在数据库中被正确地表示出来。查询也工作得很好。

modelBuilder.Entity<Save>().HasKey(c => c.SaveId).HasAnnotation("DatabaseGenerated",DatabaseGeneratedOption.Identity);
modelBuilder.Entity<Save>().HasMany(c => c.Families).WithOne(x => x.Save).HasForeignKey(x => x.SaveId);
modelBuilder.Entity<Save>().HasMany(c => c.Countries).WithOne(x => x.Save).HasForeignKey(x => x.SaveId);
modelBuilder.Entity<Save>().HasMany(c => c.Provinces).WithOne(x => x.Save).HasForeignKey(x => x.SaveId);
modelBuilder.Entity<Save>().HasMany(c => c.Pops).WithOne(x => x.Save).HasForeignKey(x => x.SaveId);
modelBuilder.Entity<Country>().HasOne(c => c.Save);
modelBuilder.Entity<Country>().HasMany(c => c.Technologies).WithOne(x => x.Country).HasForeignKey(x => new {x.SaveId, x.CountryId});
modelBuilder.Entity<Country>().HasMany(c => c.Players).WithOne(x => x.Country).HasForeignKey(x => new {x.SaveId, x.CountryId});
modelBuilder.Entity<Country>().HasMany(c => c.Families).WithOne(x => x.Country).HasForeignKey(x => new {x.SaveId, x.OwnerId});
modelBuilder.Entity<Country>().HasMany(c => c.Provinces).WithOne(x => x.Owner);
modelBuilder.Entity<Country>().HasKey(c => new { c.SaveId, c.CountryId });
modelBuilder.Entity<Family>().HasKey(c => new { c.SaveId, c.FamilyId });
modelBuilder.Entity<Family>().HasOne(c => c.Save);
modelBuilder.Entity<CountryPlayer>().HasKey(c => new { c.SaveId, c.CountryId, c.PlayerName });
modelBuilder.Entity<CountryPlayer>().HasOne(c => c.Country);
modelBuilder.Entity<CountryPlayer>().Property(c => c.PlayerName).HasMaxLength(100);
modelBuilder.Entity<CountryTechnology>().HasKey(c => new { c.SaveId, c.CountryId, c.Type });
modelBuilder.Entity<CountryTechnology>().HasOne(c => c.Country);
modelBuilder.Entity<Province>().HasKey(c => new { c.SaveId, c.ProvinceId });
modelBuilder.Entity<Province>().HasMany(c => c.Pops).WithOne(x => x.Province);
modelBuilder.Entity<Province>().HasOne(c => c.Save);
modelBuilder.Entity<Population>().HasKey(c => new { c.SaveId, c.PopId });
modelBuilder.Entity<Population>().HasOne(c => c.Province);
modelBuilder.Entity<Population>().HasOne(c => c.Save);

我从一个文件中解析整个save，所以我不能一个一个地添加所有集合。解析后，我得到了一个Save及其所有关联的集合，总共有80k个对象，其中没有一个在数据库中出现。
然后，当我调用dbContext.Add(save)时，它需要大约44秒来处理，RAM使用量从100mb上升到大约700mb。
然后，当我调用dbContext.SaveChanges()时（我也尝试了EF扩展中的常规BulkSaveChanges()方法，没有明显的区别），它需要额外的60s，RAM使用率高达1.3Gb。
这是怎么回事？为什么这么长时间和这么多的内存使用？实际上传到数据库只需要大约最后5秒钟。
PS：我也试过禁用变化检测，没有效果。
PS2：实际使用情况和注解中要求的完整代码：

public class HomeController : Controller
{
    private readonly ImperatorContext _db;

    public HomeController(ImperatorContext db)
    {
        _db = db;
    }

    [HttpPost]
    [RequestSizeLimit(200000000)]
    public async Task<IActionResult> UploadSave(List<IFormFile> files)
    {
        [...]
        await using (var stream = new FileStream(filePath, FileMode.Open))
        {
            var save = ParadoxParser.Parse(stream, new SaveParser());
            if (_db.Saves.Any(s => s.SaveKey == save.SaveKey))
            {
                 response = "The save you uploaded already exists in the database.";
            }
            else
            {
                 _db.Saves.Add(save);
            }
            _db.BulkSaveChanges();
        }
        [...]
    }

}