I'm having this problem for a long time.
I don't know if it is only my problem due to an improper use of the
Dolphin Packages or its know and accepted by the community. I have ~
200 packages some of them with a lot of direct references to globals
(this is autogenerated code).
When I turn on "show status icons" on the prerequisites pane sometimes
the calculation takes between 10 a 30 minutes, in the middle I take my
Yoga course.
I think that can be a problem strictly related to the package
organization, but in that case where is the cookbook for the "fast
prerequisites calculation"? or I should take more yoga? :D