Optimizing duplicated DAX expressions using variables

This video describes how to use variables to optimize the performance of DAX expressions containing multiple instances of the same measure or the same sub-expression.
There are two related articles and downloads:
Optimizing duplicated DAX expressions using variables
Optimizing IF conditions by using variables

If you are new to variables, watch this video first – it explains how the evaluation of a variable works:
Evaluation of variables in DAX

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