I DID READ IN SOME DUSTY OLD TOME of a forgotten ability demonstrated by certain Witches to stunt time. The ability to age slowly. The meta-chronologic power was cultivated, not inherent. It's like the speed on the legs of a cheetah: every cub of the spotted wild cats is born with long legs, but very few of them grow to really achieve the potential of running fàst as Ferraris. It wasn't explained in great details, but the book had admitted it depended on the level of power said sorcerer was packing.
Very few Witches use more than the latent percentage of Flame in spellcasting during their lifetime, but say, a mage were to practice until he could summon fire with a finger's snap, and call on ice with a flick of the wrist, such sorcerer would likely outlive the others. Simply put, the Spiritflame blesses its wielders with more than just access to its pulsing energy. It also grants near immortality. Wield enough of the Flame, and you just might live forever.