The only additional advice I can think of beyond what I have already listed in the linked article is maybe you need a new development machine with more power, faster drives etc. Visual Studio is a beast and mojoPortal is a large solution with lots of projects and files. Wish I had easier advice for you but I've already given the information that I know, I don't know of any other tips or I would already include them in that article.
You can remove resx files for languages you are not using from the /App_GlobalResources folder and you can remove extra skins that you are not using, that may help a little but I doubt it will make any drastic improvement.