Protons can sporadically appear and disappear. They are subatomic and infinitely small and of almost no mass.
The universe could also have been created in a similar fashion, and will disappear in a similar fashion. But becausue of its mass, there is more inertia and time distorts and gets slower.
For a proton to instantaneously appear and then disappear almost immediately later seems really fast to us. It can happen because of its close-to-nothing mass and almost no inertia.
Measuring the age of a human in proton years makes it seem really long. Measuring the age of the earth in human years makes it seem very long. Measuring the age of our galaxy in earth years makes it seem really really long because of its mass. And measuring the age of the universe in galaxy years makes it seem really really (really) long. What happens if we measure the age of whatever the universe is part of in universe years? Probably long to the point where time stops completely, just like before the big bang.
Each step involves more mass, more mass involves more inertia and more inertia means slower time or a slower cycle. So, the universe could be just like the proton that appears from nowhere and disappears as quick, but on a universally grander and slower scale.
We are so small and live such a small fragment of this entire process that it seems eternal to us.