I though this question was pertiaing to if function.
Max if you can help I have spreedsheet with a very complex
series of vlookup fromulas pull off a data base that is
500,000 deep and about 15 columns out.
The mail data page is set down 25000 rows right now.

It was running good speed was super but efficient.
The whole thing is driven off a phone #, completely unique and
in ascending order.

The problem is that In the main data page can not have duplicate
phone # entry, it tells us a lot, very important to the concept.

I incerted,
=IF(COUNTIF($b$1:$b$25000,a1)1,"TRUE","FALSE")

now the spreedsheet is so slow it can barly run.any sujjestions