Does if(is blank()) provide efficiencies

[PureBluff]

I just got sent a spreadsheet, obviously written by someone who doesn't actually use it, with countless vlookups against huge, whole column arrays!

I've shortened all those ranges down and converted to index/match which has obviously helped massively.

Im thinking to change to if(isblank(A1),"",lookup formula)

My train of thought is that the isblank will use less computing power to return true (majority of the lookups) & the more intensive formula (lookup) will only be calculated if cell isn't blank.

Is that correct?

Thanks!

 

[joeu2004]

Im thinking to change to if(isblank(A1),"",lookup formula)
My train of thought is that the isblank will use less computing power to return true (majority of the lookups) & the more intensive formula (lookup) will only be calculated if cell isn't blank. Is that correct?

Yes. For the Excel IF function, if the conditional expression is TRUE, only the (first) value-if-true expression is evaluated. In your case, it returns the null string.

But I would write IF(A1="","",lookup...). The advantage is: A1 might look blank because it contains an expression that conditionally returns the null string, just like yours.

IMHO, the only time that we should use ISBLANK is to distinguish between a truly empty cell (no value) and a cell that looks blank because its value is the null string.