Gallifrey's time stream

Gallifrey existed in both N-Space and an exclusive time stream separate from the rest of history. This granted the Gallifreyans higher power over time, but came to have drawbacks as Gallifrey's history progressed. Romana II believed that this made the planet a temporal anomaly, (PROSE: Lungbarrow) but The Book of the War indicated that this enclave of the continuum made the planet the very core of history. (PROSE: The Book of the War)

Romana indicated that this exclusive time stream existed long before the Time Lords, giving the ancient Pythia a sensitivity towards time and its movement. (PROSE: Lungbarrow) Ancient Gallifrey contained the Crevasse of Memories That Will Be, the chasm through which time was poured into the universe by its Goddess. The Pythia got their powers from the Crevasse, (PROSE: Cat's Cradle: Time's Crucible) suggesting it to be the time stream's source. (PROSE: Lungbarrow)

Following the Pythia's fall, Rassilon brought the Eye of Harmony to Gallifrey to give the planet a powerful stability. However, the Eye's stability (PROSE: Gallifrey - Notes on the Planet's Background) slowed down the time speed "metabolism" of Gallifrey's time stream in relation to the wider Universe, making it like "a clock that's losing perhaps a second every hour and [is] getting slower all the time." (PROSE: Lungbarrow) In Auld Mortality's universe, the Doctor said that Earth was different from Gallifrey because it had an ongoing history. (AUDIO: Auld Mortality)

Contrary to some of the above details, The Book of the War described the Homeworld's exclusive space and time of its own as being created during the anchoring of the thread, when the planet removed from the Spiral Politic and re-engineered into a biodata-enabled receiver and processor of information, becoming the central node of history. (PROSE: The Book of the War)