如何优化慢LINQ查询？

Question

我尝试删除使用contains（）的语句并使用skip（）take（） 但是执行仍需要很长时间

    public JsonNetResult GetList(C.Lib.ListParam param, string type, DateTime? WorkDate, string MNo, string ANo, string AName, string Specifi, string PNo, string SName, string PType, string OrNo)
    {
        var idObj = (mis.Models.Security.CIdentity)Csla.ApplicationContext.User.Identity;
        var c = new mis.Models.CEntities();
        var targetList = (from obj in c.WorkOrders
                          join obj2 in c.Partners on obj.PartnerId equals obj2.PartnerId
                          join obj3 in c.Assets on obj.AssetsId equals obj3.AssetsId
                          join obj4 in c.WorkOrderItems on obj.WorkOrderId equals obj4.WorkOrderId
                          join obj5 in c.WorkItems on obj4.WorkId equals obj5.WorkId
                          join obj6 in c.Products on obj3.AssetsId equals obj6.AssetsId
                          where true && obj.TenantId == idObj.TenantId && obj2.Customer == true && obj.WorkOrderStatus <= 1
                          select new
                          {
                              WorkProgressId = obj.WorkOrderId,
                              OrderNo = obj.InOrderItem.OrderItem.Order.OrderNo,
                              ProductType = obj5.ProductType,
                              WorkOrderId = obj.WorkOrderId,
                              MakeQty = obj.MakeQty,//delete some column
                              PrepaidDate = obj.PrepaidDate,
                              CompleteDate = (from subobj in c.WorkOrderItems
                                              where subobj.WorkOrderId == obj.WorkOrderId && subobj.CompleteDate != null
                                              orderby subobj.CompleteDate descending, subobj.WorkItem.WorkNo descending
                                              select subobj.CompleteDate).FirstOrDefault(),

                              WorkNoName = (from subobj in c.WorkOrderItems
                                            where subobj.WorkOrderId == obj.WorkOrderId && subobj.CompleteDate != null
                                            orderby  subobj.WorkItem.WorkNo descending
                                            select new { WorkNoName = subobj.WorkItem.WorkNo + " " + subobj.WorkItem.WorkName }).FirstOrDefault().WorkNoName,

                          });
        targetList = targetList.GroupBy(x => x.MakeNo).Select(x => new
        {
            WorkProgressId = x.FirstOrDefault().WorkOrderId,
            OrderNo = x.FirstOrDefault().OrderNo,
            ProductType = x.FirstOrDefault().ProductType,
            WorkOrderId = x.FirstOrDefault().WorkOrderId,
            WorkOrderDate = x.FirstOrDefault().WorkOrderDate,
            OrderQty = x.FirstOrDefault().OrderQty,
            MakeQty = x.FirstOrDefault().MakeQty,
            PrepaidDate = x.FirstOrDefault().PrepaidDate,//delete some column
            CompleteDate = x.FirstOrDefault().CompleteDate,

            WorkNoName = x.FirstOrDefault().WorkNoName
        }).OrderByDescending(x => x.WorkOrderDate).ThenByDescending(x => x.WorkNoName);

        param.SetCount(targetList);
        targetList.OrderByDescending(x => x.WorkOrderDate).ThenByDescending(x=> x.WorkNoName);
        var tk= targetList.Skip((param.Page - 1) * param.Rows).Take(param.Rows);
        return JsonNetHelper.ReturnData(param,tk);
    }

我想知道优化它的最佳方法是什么？或者查询分析器会为我做那个吗？