Не уверен, что словарь поможет. Думаю, скорость увеличится, если окраску салона делать сразу, а не по ячейкам. Поэтому попробуйте этот код, пожалуйста:
Sub colorInterior()
Dim sh As Worksheet, rngB As Range, rngY As Range, rngR As Range
Dim LastRow As Long, lastColumn As Long, i As Long, j As Long
Set sh = Sheets(1)
LastRow = sh.Range("A" & Rows.count).End(xlUp).row
lastCol = sh.Cells(1, Columns.count).End(xlToLeft).Column
For i = 2 To LastRow
For j = 1 To lastCol
If sh.Cells(i, j).Value = "Reportable" Then
If rngB Is nothint Then
Set rngB = sh.Cells(i, j)
Else
Set rngB = Union(rngB, sh.Cells(i, j))
End If
ElseIf sh.Cells(i, j).Value = "Abnormal" Then
If rngY Is nothint Then
Set rngY = sh.Cells(i, j) '.Interior.ColorIndex = 36 ' yellow
Else
Set rngY = Union(rngY, sh.Cells(i, j))
End If
ElseIf sh.Cells(i, j).Value = "Critical" Then
If rngR Is nothint Then
Set rngR = sh.Cells(i, j) '.Interior.ColorIndex = 38 ' red
Else
Set rngR = Union(rngR, sh.Cells(i, j))
End If
ElseIf v.Value = "Normal" Then
'here you maybe need to set interior like none
End If
Next j
Next i
rngB.Interior.ColorIndex = 37 ' blue
rngY.Interior.ColorIndex = 36 ' yellow
rngR.Interior.ColorIndex = 38 ' red
End Sub