Linq - Query on 2 Lists Optimization - sql-server

Question

I am having 2 Lists & I am querying on this 2 List. Both the List are populated with huge data. So the query is taking long time.
When I usually face this performance issue, I simply convert SQL queries & run them directly & get the result in a datatable. But this time I cannot do this as these 2 are not tables but Lists of Models.
How to Optimize this Query or what else should i do?
Code :-
List<TempInOut> listTempInOut = new List<TO_TempInOut>();
List<ShiftSchedule> tempShiftSch = new List<TO_TempInOut>();
var data = (from B in tempShiftSch
from C in listTempInOut
where
B.CompanyId == companyId &&
C.CompanyId == companyId &&
B.EmployeeId == C.EmployeeId &&
C.InDate >= StrOutStart &&
C.InDate <= StrOutEnd &&
B.ShiftId == item.ShiftCode &&
B.ShiftDate == tempInputDate
select new
{
C.EmployeeId,
C.InDate,
C.Time_Date1
}).ToList();

Answer 1

Implement an IEqualityComparer for your types, use HashSet for each collection, and use the HashSet.Intersect method to get your output.

Answer 2

You can simplify your query to two stepsand compare time.
I am thinking of something like that.
var listTempInOutResult = listTempInOut.Where(C => C.CompanyId == companyId
&& C.InDate >= StrOutStart
&& C.InDate <= StrOutEnd);
var employessIds = listTempInOutresult.Select(x => x.EmployeeId).ToList();
var data = tempShiftSch.Where(B => employessIds.Contains(B.EmployeeId)
&& B.CompanyId == companyId
&& B.ShiftDate == tempInputDate
&& B.ShiftId == item.ShiftCode)
.Select(C=> new
{
C.EmployeeId,
C.InDate,
C.Time_Date1
}).ToList();

Answer 3

if you are working with iqueryable it would be better to use joins.
see this StackOverflow question