This feels off to me -- maybe @yuhunglin & @ctweney & I should confab? Either of the following looks a bit more enticing (to me, anyway, and maybe missing blockers):

(A) Just call the MyClasses model or the Canvas proxy & get it cached if it's cached (or cache it if it's not)
or
(B) (less attractive, but explicit) Somehow chain the call to the Canvas activity processor to the close of the My Classes feed.

I face a similar pattern for the notifications work, because My bSpace Announcements depends on My (Sakai) Classes/Groups.