I think the Enterprise uses a quantum slipstream or transwarp drive in the reboot. Its the only workable explanation for the travel time to Kronos of approximately two minutes. I have read on here that Kronos is 90 light years from Earth? I don't know the source of that but for the purpose of this thread I will use that figure. I am aware the Enterprise travels at the speed of plot but perhaps not at a speed that ruins the premise of certain Star Trek shows? or contradicts certain Trek episodes (Q Who?)
The Vulcan travel time in the last movie is ambiguous but I think a few hours. Still really fast. It indicates Kronos is either way closer to Earth than Vulcan or the Enterprise has upgraded its slipstream drive this time
I think its about 0.75 light year per second for Earth to Kronos based on 90 light year distance. So 75000 light years for Voyager at Star Trek Into Darkness speeds would take a day or so. The whole galaxy is within a days warp.
If the Enterprise warps into the cosmos away from Earth at Star Trek Into Darkness speeds for 3 years of its 5 year mission it will travel: 71 million light years.
Only one ship has gone faster than this, USS Enterprise, NCC-1701-A travelled to the centre of the galaxy in 6.1hours from Nimbus 3. Approx 30,000 ly and almost twice the speed of the Enterprise in STID.