The idea is that you've already dismantled the stars and stockpiled all the energy in the universe, to use at your leisure. (i.e. everyone lives around black holes they can throw mass into to reap the bawking radiation). Since you have control over the last non-entropic systems, you can tune how fast the candle burns.

And you're a mind running on a computer! You were already going to experience the heat death! This is just a scheme to get the most subjective time out of it as possible. (Running slower is more efficient.)