ssas - MDX: efficient way to filter tuples where particular columns are not empty? -

suppose have mdx query this:

select measure1, measure2, measure3 on columns [region].[region].[region] on rows thecube

if wanted exclude rows 3 measures empty, use select non empty, works fast. need exclude rows both measure1 , measure2 empty, if measure3 has value - because in particular cube measure3 has value, non empty has no effect @ all.

i

select measure1, measure2, measure3 on columns filter ([region].[region].[region],         not (isempty(measure1) , isempty(measure2)) on rows thecube

and works, takes forever: order of magnitude longer non empty query above. in fact, if filter expression true, filter(..., 1=1), takes lot of time.

is there more efficient way filter out rows both measure1 , measure2 empty?

i think looking similar function nonempty. http://msdn.microsoft.com/en-us/library/ms145988.aspx here explanation between them: http://thatmsftbiguy.com/nonemptymdx/