Faster Calculation than SumProduct?

[leem]

Hello,
I have the following formula and needless to say, the calculation is very slow.

=SUMPRODUCT(--('85_08'!$A$2:$A$10800='09 YTD Auto Claims'!G38),--('85_08'!$B$2:$B$10800="A"))

Right now this formula is copied down about 4,000 rows and this will grow in double the rows by the end of the year. Plus another column which is looking for the same criteria only instead of A, it will be an I. I would greatly appreciate any help or advice in making this formula better and faster.
Thanks
Michelle

[DonkeyOte]

If you're using XL2007 use COUNTIFS over SUMPRODUCT

If running pre XL2007 use concatenation on '85_08', let's assume column C is available:

'85_08'!C2: =$A2&":"&$B2
copied down to C10800

Your SUMPRODUCT then becomes a standard COUNTIF

=COUNTIF('85_08'!$C$2:$C$10800,'09 YTD Auto Claims'!G38&":A")

Less elegant but more efficient.

[leem]

Awesome...works beautifully! Oh thank you for sharing your knowledge and so quickly.