datagrid view change color depend of status in winform application - vb.net

Question

I have a function like this:
Sub KPIColorchange()
'take 80 percenatge
Dim perc80 As Integer = 80
value80 = DefaultKPI * perc80 / 100
Dim carid As String
Dim strr As String = "select t.TBarcode as carid from Khanger_tbl k
inner join transaction_tbl t on k.transactid=t.transactID"
strr = strr + " where tid= " & tid & " and requested=1 and delivered=0 and status=3
and DATEDIFF(n, CAST(paydate AS DATETIME), GETDATE()) >=" & value80 & ""
Dim cmdr As New SqlCommand(strr, con.connect)
dr2 = cmdr.ExecuteReader
While dr2.Read
If dr2("carid") Is DBNull.Value Then
carid = ""
Else
carid = dr2("carid")
End If
Dim cnt As Integer = DGVall.Rows.Count
For i = 0 To cnt - 2
If DGVall.Rows(i).Cells(0).Value.ToString().Equals(carid) Then
DGVall.Rows(i).DefaultCellStyle.BackColor = Color.Fuchsia
End If
Next
End While
dr2.Close()
con.disconnect()
'take 100 percentage
Dim perc100 As Integer = 100
value100 = DefaultKPI * perc100 / 100
Dim str100 As String = "select t.TBarcode as carid from Khanger_tbl k
inner join transaction_tbl t on k.transactid=t.transactID"
str100 = str100 + " where tid= " & tid & " and requested=1 and delivered=0 and status=3 and
DATEDIFF(n, CAST(paydate AS DATETIME), GETDATE()) >=" & value100 & ""
Dim cmd100 As New SqlCommand(str100, con.connect)
dr2 = cmd100.ExecuteReader
While dr2.Read
If dr2("carid") Is DBNull.Value Then
carid = ""
Else
carid = dr2("carid")
End If
Dim cnt As Integer = DGVall.Rows.Count
For i = 0 To cnt - 2
If DGVall.Rows(i).Cells(0).Value.ToString().Equals(carid) Then
DGVall.Rows(i).DefaultCellStyle.BackColor = Color.OrangeRed
End If
Next
End While
dr2.Close()
con.disconnect()
End Sub
I have a grid view ,in that grid view i am loading some Requested carid we already set some time interval to Location.depend on the location time interval i have to change color in grid view
if the car requested time coming 80 percentage of location interval time then i will change to one color .
if the car requested time coming 100 percentage of location interval time then i will change to OrangeRed only this much things i am doing here..normally my datagrid view contains morethan 100 above records. this function i am calling in Timer_tick event in each one minute.
but becouse of this function my system get slow or some time system get hang.how i can optimize this code?
any help is very appreciable in advance