What rate would a porphyritic texture indicate regarding a rocks cooling history?

Would it be slow, instantly, quickly or at various rates?What rate would a porphyritic texture indicate regarding a rocks cooling history?
Various. A porphyritic texture is defined by as having two distinct grain sizes, typically aphanitic and phaneritic. By having both textures, the igneous rock is said to have cooled at two different rates, usually cools slowly (allowing for the phaneritic texture) then rapidly (creating the aphanitic texture).