Should properties be copied to variables for battery-life?

In a watch-face, should frequently used properties be copied to variables instead of being always accessed by getProperty? 

Will a battery-life benefit from accessing the variable instead reading the property if (let's say) 20 of properties are read tens times each second? 

The drawback of variables is a memory consumption. My watch face is hitting a memory limits during a hourly background data loading.

Or how to think about properties vs. global variables.