The torture of that place is the separation from God and the despair of one's own choices.
The "punishment" of residing in eternity apart from God is not based on the finite lifespan of the created or the finite perception of good and bad, but the infinite chasm created when one offends in any manner against an infinitely holy standard. Neither relative goodness nor time bear on this standard of perfection.
The infinite crime must be judged with infinite justice.
That's my take.
The "sinned against an infinite god" argument I've heard before. It doesn't work.
Let's see, what you are saying is that since God is infinite the "crime" of not believing in him is therefore infinite? So the power and, let's call it wealth, of the "victim" of the crime determines the severity of the crime? God is infinite therefore snubbing Him calls for infinite punishment? In much the same way that stealing $10 from Bill Gates is a much more serious crime than stealing $10 from me.
Maybe Bill Gates would find that an attractive approach, but I'm afraid I can't buy into that. Mind you, I'm not terribly inclined to buy the flip side, the "he (the victim) can afford it therefore the crime is less severe" argument either, but infinite punishment for what amounts to indifference or maybe snubbing?
Even if the "suffering" is "despair over one's own choices" there really needs to come a time when one has suffered enough. A time when "Okay, you've been in time-out long enough. You can come back to the family room."
I mean, I could see a "you didn't pay any attention to me for the 73 years you were alive so you're going to stay in outer darkness for 73 years and a day as a punishment."
But forever?
Justice?
"You keep using that word. I do not think it means what you think it means."