Speculation on the universe, 50 trillion years from now

The universe being nearly out of energy forces the evolution of beings that exist on a vast time scale, using small amounts of energy, where events like the expansion of a star from a normal star to a red-giant is visible to these beings like it was on an hour-long timescale for normal humans. These beings, the future us, would have lifespans billions of years long, or essentially infinite. Think the opposite of the hyper-accelerated beings on the original "Star Trek." Of course, this is all speculation.