My spreadsheet looks like this:

parcel type tax penalty cost
123 0000 10.00 1.50 30.00
234 2345 5.55 .55 10.00
356 5040 11.11 1.12 3.00
945 2145 7.00 .70 1.50

(My spreadsheet has 135,000 different parcels)

When the parcel changes, I need subtotals for the tax, penalty and
cost.

After 30 minutes, subtotals have been inserted for only 15,000
parcels. At this rate, it'll take almost 5 hours to complete.
Is there any way to speed up the subtotalling?