An alternative to the conditional calc you've using
could be making a 4-column table from your calc
and blending it to your datasource.
It could be possible only if your [Risk Rating],
[Market] and [Box Color] are Dimensions.
Moreover, the two values for [Market] should be
'High' and 'Other' -- to use an equality (==) for a blend.
As for the processing speed, it depends on many factors,
and your IF ... ELSEIF .... calculation could have an impact
(as well as a blend).