We did a lot of performance improvements for the Dynamics AX 2012 R2 Excel Add-in, but there is still one scenario that causes a lot of trouble... copy and paste.
When a large data set is pasted into a field bound table, then the VSTO change tracking evaluates the changes on the entire table after each row is pasted. This is just standard VSTO behavior that we can't work-around so the original 2012 advice still holds... turn track changes off when adding a large number of new rows.
Change tracking can be turned off via: Excel -> Dynamics AX tab -> Publish drop arrow -> Publish options -> Track changes checkbox
When track changes is turned back on then each row is treated as a new row, so remove existing data before turning track changes back on. When change tracking is resumed then each new row is evaluated once, resulting in a greatly reduced time waiting for the change tracking to analyze the new data set.