Since you have not tagged your question as
theravada-only, I assume you accept answers from all traditions.
In Mahayana, we have a notion of different paths suitable for people of different predilections. The Tibetan tradition has developed two methods, somewhat similar to each other, that are said to allow a serious practitioner to achieve Enlightenment in one lifetime, or even faster.
These methods are known as Mahamudra and Dzogchen. In my understanding, both work by approximating the target state of Nirvana or suchness that Buddha's teaching culminates in. Here I will boil them down to their essential point, hoping to make them available to Internet-age students. If my presentation looks misleading or incomplete, feel free to study traditional literature or practice under the guidance of a qualified teacher.
Basically, the fastest way to Enlightenment consists in "leaving everything as is" and attaining an unwavering conviction and confidence that the regular unmodified state of things is already the "Great Perfection".
Of course, this method assumes one does not have coarse mental and emotional obscurations. In other words, this method assumes that the student is already pretty close to Enlightenment.
There is also a huge difference between taking this "view" as an operative basis of one's emotional mind versus simply thinking that "everything is perfect" when it's not -- on one hand, or simply giving up and staying a fool -- on the other.
When taken correctly, this view results in an effortless state of no attachment, no craving, no aversion, no side-taking, complete non-judgmental acceptance of "oneself" and "the world", dissolution of subject/object duality, perfect realization of metta, karuna, mudita and upekkha, cessation of all suffering, feeling of liberation or spontaneity, and absolute unconditional love.