The degree that time slows in gravity is determined by the
acceleration of the gravitational potential. Acceleration slows time.
Steady motion maintains the time rate that has been slowed by
acceleration. Both in gravity and in accelerating a frame acceleration
slows time. For every velocity which must be created by acceleration
there is a slower time rate defined by the Gamma factor. Gamma factor
in gravity acceleration field and speed produced by an acceleration
gives the slowdown of time. Zero velocity would be fastest
uncontracted time. But as Einstein said there is no absolute rest
therefor there is no absolute velocity zero. Everything has a motion
through space.

Mitch Raemsch Twice Nobel Laureate 2008