Formula Category Color Coding?

[Darius1968]

Is it by design or is it a bug that I can not apply any foreground/background color coding to formula categories as I can to regular/data driven categories? 

[Mario]

This is by design.
Formula-based categories are expensive or very expensive to update. Updating them all the time because a user has enabled the category color bar in a File Window layout would cause performance issues.

[Darius1968]

Just out of curiosity:  I was just wondering how it is that the formula category is more expensive in that it would take a performance hit before a data driven category (which allows for color coding), were color coding for formula categories to be implemented. 
It's no big deal in my workflow as I was able to set up a data driven category instead to effect what it is that I want.  Thanks.