I recently diagnosed a slow Straight Table chart. The chart contained 100K+ rows. One column contained a complex expression that returned a Y/N string flag for the column. Something like:
=if(complex expression, ‘Y’, ‘N’)
They also wanted to set the background color of the cell, green for Y, red for N. So the Expression Background Color property repeated the same complex expression to assign a color:
=if(complex expression, green(), red())
I surmised the expression was being calculated twice for each row. I changed the main expression to set a Dual().
=if(complex expression, dual(‘Y’,1), dual(‘N’,0))
The chart cell still displays the Y/N text. But now I could use 1 and 0 values on the Visual Cues pane and eliminate the Background Color expression entirely. Much faster!