I don’t know anything about this stuff, so I’ll let this quote speak for it:

PHOENIX is a general-purpose state-of-the-art stellar and planetary atmosphere code. It can calculate atmospheres and spectra of stars all across the HR-diagram including main sequence stars, giants, white dwarfs, stars with winds, TTauri stars, Novae, Supernovae, brown dwarfs and extrasolar giant planets.

What’s most interesting is the different platforms that it’s been tested on — Itanium2, P4, Athlon64, Apple G4 and DP G5, and some parallel architecture in the IBM Regatta Power4 — and the sometimes staggering benchmark results. For details, check out the Computing link, under Other Topics.

The G5 essentially blows all the other processors out of the water.