DAX Optimisation

Hi, 

Just wanted to get some pointers on optimising some DAX. I've got a series of DAX measures doing a similiar measures using sum/sumx and countrow functions. These are then in turn used in other measures to add together/subtract and divisions. 

However some are taking sometime to process and I've tried using DAX Studio which has helped pin point some of the slower measures but not sure how to optimise.

Example of a typical measure: 
Measure=

//Determined by user when changing a date slicer
VAR _StartDate = [Start Date]
VAR _EndDate = [Start Date]

RETURN
Calculate (
  SUMX('TABLE1',COLUMN1, COLUMN2),
TABLE1,[COLUMN2] = "value",
DateTBL,[DATE] >= _StartDate & 'DateTbl'[Date] <= _EndDate
)

Is there a better way of writing this?

Pretty much all my measures are like this and then I have some that just go Total = [Measure1] + [Measure2] et..

Thanks,

Ben