There is a clause in the Permanent Resident Permit Regulations for PR for investment purposes. From the SEF website:
To the citizens holding a residence permit for investment purposes and their family members, complying with the requirements provided in article 80 of the Aliens Act and wish to be granted with a permanent residence permit, a permanent residence permit for investment purposes shall be issued, exempt of the provided in article 85, n.ºs 2, 3 and 4, subparagraph b) of the same diploma (cancellation of the right due to absences from the national territory, see article 65-k of the Regulatory Decree 84/07 of 5/11, as amended). The Permanent Residence Permit for investment purposes may be subject to specific fees of analysis and issuance, to be regulated by amendments to Ordinance 1334-E/2010, of December 31.
Unfortunately, I cannot read Portuguese yet. However, on the face of it, it appears that a PR for investment pruposes does not have to spend the minimum required time for other the general PR regime. Does he/she still need to spend 7 days per year? Does he/she still need to maintain the golden visa investment? I have asked a few people in the GV business but nobody has been able to give me a convincing answer.