Calculate running total with level change

[FryGirl]

I have a table of over 22k rows and this formula simply bogs the processer down. Is there an alternative that could work better?

Book1
	A	B	C	D
1	Hdr1	Code	Hdr2	Hdr3
2	1	L	10	46
3	2	L1	23	36
4	3	L1A	12
5	3	L1B	1
Sheet1

Cell Formulas
Range	Formula
D2:D5	D2	=IF($A2<$A3,SUMPRODUCT(--(LEFT($B$2:$B$5,LEN($B2))=$B2),--(C$2:C$5)),"")

 

[Fluff]

How about

=IF($A2<$A3,SUMIFS(C:C,B:B,B2&"*"),"")

 

[FryGirl]

Thanks Fluff. That makes a significant difference.

 

[FryGirl]

Thank you Eric as well.

 

[Fluff]

Glad we could help & thanks for the feedback.