Query Optimization - Suggestions? - performance

Question

I am hoping someone can help me understand this XML Showplan for a long running query. This query comes from a Crystal Report developed by the software vendor that is very slow running, and I'm trying to convert it to an SSRS report while speeding the query up.
Here is a link to the Execution Plan - File hosted on File Dropper.
And here is the actual query itself:
Select Distinct
CD.desclong [Center],
CD.CenterType,
Sub.Description [SubCenter],
Org.Description [OrgCenter],
CO.CodeID [CenterC],
Sub.CodeID [SubCenterC],
Org.CodeID [OrgCenterC],
Reg.Description [Region],
Reg.CodeID [RegionC],
Rec.CodeID [RecID],
Rec.Description [RecName],
Rec.NickName [RecNickName],
Acct.AccountID [AcctCharCode],
DM.DriveID,
DM.ExternalID [DriveExtID],
DM.FromDateTime [DriveDate],
dbo.getShiftProductProjectionList(DSD.shiftid) [ProductProjections],
dbo.getShiftProcedureProjectionList(DSD.shiftid) [ProcedureProjections],
dbo.getShiftMobileList(DSD.shiftid, '1,2,3') [MobileSetups],
LD.LocationName [LocationName],
Case DM.OwnerType
When 1 Then FSM.DisplayName
When 0 Then Acct.InternalName
End [OwnerName], Acct.ExternalID [AcctExtID], SM.ExternalID [SiteExtID],
Stat.StatusText [DriveStatus],
DSD.ShiftID,
DSD.ShiftStart,
DSD.ShiftEnd,
DT.EarlyShiftStart,
DT.LateShiftEnd,
Changes.*,
dbo.getOriginalProcedureProjection(Changes.dsprocshiftid, Changes.dsprocprocedureid) [OriginalProjection],
(Select Top 1 DescMed From Production.[dbo].QuickCodes where CodeValue = 'ACTEXTIDTAG') [ActExtIDTag],
(Select Top 1 DescMed From Production.[dbo].QuickCodes where CodeValue = 'SITEEXTIDTAG') [SiteExtIDTag],
(Select Top 1 DescMed From Production.[dbo].QuickCodes where CodeValue = 'DRVEXTIDTAG') [DrvExtIDTag],
Case When (Changes.TableName = 'DriveShiftProcedureDetail') Then (Select Top 1 projectionid From driveshiftproceduredetail where uniquekey = Changes.owneruniquekey) else null end as ProjectionID
From
Production.[dbo].rpt_DriveMaster DM
Join Production.[dbo].rpt_DriveShiftDetail DSD on DSD.DriveID = DM.DriveID
Join Production.[dbo].CriticalDriveChanges Changes on (Changes.SourceDriveID = DM.DriveID and Changes.SourceShiftID = DSD.ShiftID and
Production.[dbo].returnDateTime(year(Changes.ChangeWhen),month(Changes.ChangeWhen),day(Changes.ChangeWhen)) between '01/04/2015' and '01/04/2015')
And
(
(
(Changes.TableName='DriveShiftProcedureDetail' and Changes.ColumnName='projection')
or
(Changes.TableName='DriveShiftDetail' and (Changes.ColumnName='ShiftStart' or Changes.ColumnName='ShiftEnd'))
or
(Changes.TableName='DriveShiftDetail' and Changes.ColumnName='StaffRequested')
or
(Changes.TableName='DriveShiftDetail' and Changes.changetype='Delete')
or
(Changes.TableName='DriveMaster' and Changes.ColumnName='StatusID' and Changes.NewValue='5')
or
(Changes.TableName='DriveMaster' and Changes.ColumnName='FromDateTime')
or
(Changes.TableName='DriveShiftRoleTimeDetail' and Changes.ColumnName='Lead')
or
(Changes.TableName='DriveShiftRoleTimeDetail' and Changes.ColumnName='TravelTo')
or
(Changes.TableName='DriveShiftRoleTimeDetail' and Changes.ColumnName='Setup')
or
(Changes.TableName='DriveShiftRoleTimeDetail' and Changes.ColumnName='Breakdown')
or
(Changes.TableName='DriveShiftRoleTimeDetail' and Changes.ColumnName='TravelFrom')
or
(Changes.TableName='DriveShiftRoleTimeDetail' and Changes.ColumnName='WrapUp')
)
and
(Changes.ChangeWho<>'RMADMIN')
)
Join Production.[dbo].rpt_DriveStatusDef Stat on Stat.StatusID = DM.StatusID
Join Production.[dbo].DriveTimes DT on DT.DriveID = DM.DriveID
Left Outer Join Production.[dbo].rpt_CenterDetail CD on CD.CenterID = DM.centerid
Left Outer Join Production.[dbo].IDViewRegion Reg on CD.Region = Reg.CodeID
Left Outer Join Production.[dbo].IDViewOrgCenter Org on CD.OrgCenter = Org.CodeID
Left Outer Join Production.[dbo].IDViewOrgSubCenter Sub on CD.OrgSubcenter = Sub.CodeID
Left Outer Join Production.[dbo].IDViewCollectionOp CO on cd.centerid = CO.CodeID
Left Outer Join Production.[dbo].IDViewRecruiter Rec on Rec.CodeID = DM.RecruiterID
Left Outer Join Production.[dbo].rpt_Accounts Acct on Acct.AccountID = DM.AccountID
Left Outer Join Production.[dbo].rpt_FixedSiteScheduleMaster FSM on FSM.DrawID = DM.DrawID
Left Outer Join Production.[dbo].rpt_LocationDetail LD on LD.LocationID = DM.LocationID
Join Production.[dbo].rpt_SiteMaster SM on SM.SiteID = DM.SiteID
Where
(dbo.returnDateTime(year(DM.Fromdatetime),month(DM.Fromdatetime),day(DM.Fromdatetime)) between '01/04/2015' and '01/04/2015')
or (dbo.returnDateTime(year(Changes.previousdrivedate),month(Changes.previousdrivedate),day(Changes.previousdrivedate)) between '01/04/2015' and '01/04/2015')
Here is the actual execution plan using Set Statistics XML On
Execution Plan
Thanks!
I removed the functions for returnDateTime and used the following instead:
-- In the FROM statement
Join Hemasphere_Dev.[dbo].CriticalDriveChanges Changes on (Changes.SourceDriveID = DM.DriveID And Changes.SourceShiftID = DSD.ShiftID And Changes.ChangeWhen Between '01/01/2015' And '01/15/2015')
--Hemasphere_Dev.[dbo].returnDateTime(year(Changes.ChangeWhen),month(Changes.ChangeWhen),day(Changes.ChangeWhen)) between '01/01/2015' And '01/15/2015')
-- In the WHERE statement
DM.FromDateTime Between '01/01/2015' And '01/15/2015'
Or Changes.PreviousDriveDate Between '01/01/2015' and '01/15/2015'
--(dbo.returnDateTime(year(DM.FromDateTime),month(DM.FromDateTime),day(DM.FromDateTime)) Between '01/01/2015' And '01/15/2015')
--Or (dbo.returnDateTime(year(Changes.previousdrivedate),month(Changes.previousdrivedate),day(Changes.previousdrivedate)) Between '01/01/2015' And '01/15/2015')
The query actually ran slower this way.