I hope you are fine.
In Portugal we have two diferent laws which regulate the Portuguese citizenship applications.
One is the portuguese citizenship law and the portuguese citizenship regulation.
According to tportuguese citizenship law (article 6.º http://www.pgdlisboa.pt/leis/lei_mostra_articulado.php?nid=614&tabela=leis) you need to fulfill the following :
a. Be older than 18 years;
b. Be a legal resident of Portugal for at least 5 years ( Which you proof through the addition of your Golden Visa residence permits validity. Your lawyer may get a certificate from SEF which proofs this.);
c. Know the portuguese language (Pass the A2 exam as refered by @tkrunning above);
d. Not have been sentenced for a crime with a punishment of 3 years or more.
Besides those, there is a subjective requirement previewed in the portuguese citizenship regulation (http://www.pgdlisboa.pt/leis/lei_mostra_articulado.php?nid=895&tabela=leis&so_miolo=).
This regulation was not yet updated with the legal time frame of 5 years. It still states 6 years (article 19.º 2 b).
Article 56.º 2 a) states that the responsable entity may oppose itself to your citizenship application if there is a absence of an effective connection to the national community.
e. Connection to the national community; ( This is a very subjective requirement in which all connections with Portugal count (ex: flights to Portugal, the prove you used to renew your Golden Visa residence permits, portuguese tax identification numbers, public health insurance (SNS), portuguese bank account, the Golden Visa residence permit itself, etc…). There is no magic formula to comply with this requirement. It is subjectively decided by the competent entity.
Owning property for some time would count as additional connection with the country ( Owner of property, utility bills, tax return in Portugal over income generated by that property, etc…).
Answer: According to law there is no need for a permanente residency to be able to apply for the Portuguese Citizenship. But as the portuguese citizenship regulation was not yet updated, the request for citizenship is still made after 6 years, instead of 5 years how they preview to regulate in the next months/years when updating the portuguese citizenship regulation.