问查询到列表的转换非常慢

EN

data = new DataContext();

var core = from item in data.Items
           where countryIDs.Contains(item.CountryId)
           && indicatorIDs.Contains(item.IndicatorId)
           orderby item.Indicator
           select item;

var x = from item in core.Distinct()
        group item by new { item.IndicatorId, item.Indicator }
            into indicator
            select new
            {
                IndicatorID = indicator.Key.IndicatorId,
                IndicatorDescription = indicator.Key.Indicator,
                Genders = from g in core
                          where g.Gender != null
                          && g.IndicatorId == indicator.Key.IndicatorId
                          select new Gender
                          {
                              GenderID = g.GenderId,
                              GenderDescription = g.Gender
                          },
                HasGender = (from g in core
                             where g.Gender != null
                             && g.IndicatorId == indicator.Key.IndicatorId
                             select g.GenderId).Count() > 0,
                AreaTypes = from rat in core
                                     where rat.IndicatorId == indicator.Key.IndicatorId
                                     && rat.AreaType != null
                                     select new AreaType
                                     {
                                         AreaTypeId = rat.AreaTypeId,
                                         AreaDescription = rat.AreaType
                                     },
                HasAreaType = (from rat in core
                                        where rat.IndicatorId == indicator.Key.IndicatorId
                                        && rat.AreaType != null
                                        select rat.AreaTypeId).Count() > 0,
                Sectors = from s in core
                          where s.IndicatorId == indicator.Key.IndicatorId
                          && s.Sector != null
                          select new Sector
                          {
                              SectorID = s.SectorId,
                              Title = s.Sector
                          },
                HasSector = (from s in core
                             where s.IndicatorId == indicator.Key.IndicatorId
                             && s.Sector != null
                             select s.SectorId).Count() > 0
            };

List<Indicator> indicators = new List<Indicator>();
Indicator i = new Indicator();
foreach (var item in x)
{
    i = new Indicator()
    {
        IndicatorID = item.IndicatorID,
        IndicatorDescription = item.IndicatorDescription,
        Genders = item.Genders.ToList(),
        AreaTypes = item.AreaTypes.ToList(),
        Sectors = item.Sectors.ToList(),
        HasGender = item.HasGender,
        HasAreaType = item.HasAreaType,
        HasSector = item.HasSector
    };
    indicators.Add(i);
}
return indicators;