Something came to my mind today:
A Deva-born-Sakadagami will attain Nibbana faster than a Brahma-born-Anāgāmi, right? Since the life span of the latter is much much longer than the former. A Deva-born-Sakadagami, after attaining the fruition of Sakadagami in the human realm, gets reborn as a once-returner to Kama Loka in the deva realm and attain Nibbana from there. Similarly for the case of the Brahma-born-Anāgāmi where he will be dwelling in the Pure Abodes for a much longer time before attaining Nibbna. If that is the case, a Sotāpanna can also attain Nibbana faster than a Deva-born-Sakadagami and Brahma-born-Anagami. For instance, a person attains Sotāpanna fruition in this life time. Assuming he is the laziest Sotāpanna around and that he is to max out the 7 rounds of bhava entirely in the human realm (obviously he cannot fall into woeful planes. Phew! Crisis averted!). The maximum time he would have to spend before attaining Nibbana is only thousands of years versus millions of years and aeons for the case of a Deva-born-Sakadagami and Brahma-born-Anāgāmi, respectively.