SQL Server 2012 – How to Improve SQL Query Performance

Related to one of my previous questions: How to select a subset from a query result

I now have this Query:

CREATE TABLE #JourneyLogs
    (
        JourneyStartId INT,
        JourneyEndId INT,
        AssetId INT,
        [Event] INT,
        JourneyStart DATETIME,
        JourneyEnd DATETIME,
        GeofenceId INT,
        JourneyDistanceKM FLOAT,
        JourneyTime INT
    )

    INSERT INTO #JourneyLogs
        SELECT 
              JourneyStartId
            , JourneyEndId
            , AssetId
            , [Event]
            , JourneyStart
            , JourneyEnd
            , GeofenceId
            , JourneyDistance = ROUND((SUM(DistanceCoveredK) / 1000), 3, 1)
            , JourneyTime
        FROM (
            SELECT 
                 JourneyStartId = ignOn.iVehicleMonitoringId
                ,JourneyEndId = ignOff.iVehicleMonitoringId
                ,AssetId = ignOn.iAssetId
                ,JourneyStart = DATEADD(hour, @fGmtOffSet, ignOn.dtUTCDateTime) 
                ,JourneyEnd = DATEADD(hour, @fGmtOffSet, ignOff.dtUTCDateTime)
                ,[Event] = ignOff.eEventCode
                ,DistanceCoveredK = p.sptGeoLocaitonPoint.STDistance(
                                        LEAD(p.sptGeoLocaitonPoint) OVER(PARTITION BY ignOn.iAssetId, ignOn.dtUTCDateTime ORDER BY ignOff.dtUTCDateTime))
                ,GeofenceId = ignOn.iGeofenceId
                ,JourneyTime = DATEDIFF(SECOND, ignOn.dtUTCDateTime, ignOff.dtUTCDateTime)
            FROM VehicleMonitoringLog ignOn
            CROSS APPLY (
                SELECT top(1) iVehicleMonitoringId, eEventCode, dtUTCDateTime, sptGeoLocaitonPoint 
                FROM VehicleMonitoringLog WHERE 
                iAssetId = ignOn.iAssetId AND dtUTCDateTime > ignOn.dtUTCDateTime AND eEventCode = 2
                ORDER by dtUTCDateTime
            ) ignOff
            INNER JOIN VehicleMonitoringLog p ON p.iAssetId = ignOn.iAssetId AND p.dtUTCDateTime >= ignOn.dtUTCDateTime AND p.dtUTCDateTime <= ignOff.dtUTCDateTime
            WHERE 
                ignOn.dtUTCDateTime > @utcStartDate AND ignOn.dtUTCDateTime < @utcEndDate
                AND ignOn.iAssetId in (Select iAssetId FROM #tblAssets)
                AND ignOn.eEventCode = 1
        ) g

        GROUP BY AssetId, [Event], GeofenceId, JourneyStart, JourneyEnd, JourneyTime, JourneyStartId, JourneyEndId

This takes 19 seconds and returns 4830 rows, with STATISTICS IO:

Table '#JourneyLogs________________________________________________________________________________________________________000000000148'. Scan count 0, logical reads 4864, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 146540, logical reads 857406, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'VehicleMonitoringLog'. Scan count 9719, logical reads 64578, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table '#tblAssets__________________________________________________________________________________________________________000000000147'. Scan count 1, logical reads 1, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Warning: Null value is eliminated by an aggregate or other SET operation.

(4830 row(s) affected)

Execution Plan: Here

Is there a way to improve this query?