Sumproduct Alternative

I have Worksheet("Sheet1") that has roughly 300,000 rows
and Worksheet("Totals") that has 2,400 rows

Sheet1 has transactions 1 to a line with company (Column D) Revenue (Column R) and Cost (Column S)

Some companies have more than one name such as: Law office of Jones / Jones LLC
I have arranged the multiples in adjacent columns (E,F,J etc...)

Most Companies have one name - some schools have multiple names

Currently I have:

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in Column B and

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in column C
Copied down through row 2,400

This kills my computer

What macro would you suggest that would quickly determine if a cell is empty, find and sum the instances on sheet1, then move on?

Have you tried a Pivot Table?

names don't match so it would be no good.
I need to sum the cost of Law office of Jones & Jones LLC - Pivot table would keep them separate.
that is why my sumproduct has $E2:$Z2 so all possible names can be listed - then looked up and summed from sheet1