I have a spreadsheet containing 25000 rows of data. For each row, I am
trying to calculate a weighted average cost (rate) based upon certain
criteria. Here is an example of the calculation that appears in cell D2
(same basic formula is copied down for all rows):

=iferror(sumif($A$2:$A$25000,$A2,$B$2:$B$25000)/sumif($A$2:$A$25000,$A2,$C$2:$C$25000),0)

Here is an example of what the data in A-C, with the calculated result of my
formula in column D:

A B C D
(calculation)
Jones $10000 1,000 $7.714
Jones $ 5000 2,000 $7.714
Smith $25000 3,000 $7.368
Jones $12000 500 $7.714
Smith $30000 4,000 $7.368
Smith $15000 2,500 $7.368

This formula works fine & gives me the result I need, HOWEVER, the way the
formula gets populated is thru a macro that copies/pastes the formula down
after the "data" (col's A-C) is imported into the worksheet. This copy/paste
process takes a LONG time to recalculate for each of the 100 columns that
contain a similar formula to what I have in column D. The problem is, I
cannot "turn off" the calculation because I need to have the result of some
columns before I can calculate others. The, when the macro is finished
running, it does a copy/paste values over all of the columns to "lock in" the
result.

Can anyone provide a suggestion in terms of a different formula or function
that can help me achieve a more optimal calculation speed? Currently, it
takes nearly 90 minutes to "calculate" this worksheet when the data is
imported (based upon 20-25,000 rows of data x 100 columns of SUMIF
calculations.)