Mapping the speed-up key to CapsLock is already possible for the player.
What's
not currently possible, and which IMHO is needed for those long aggravating jaunts from one diagonal corner of the map to the opposite corner, is a
greater degree of speed-up. I'm suggesting the future addition of options such as 2X, 4X, 6X and perhaps even faster. At 2X it's still as slow as waiting for paint to dry. On a long haul, I actually get up from the computer and go fix myself a sandwich and a cup of tea. At least half of the time, when I return, my fleet
still has not made its destination when I return to the computer!
So: let's have Shift (or whatever key) open up a very small panel along one edge of the screen where we can Page Up / Page Down, or Up Arrow / Down Arrow, through multiple faster rates for the precession of time. Once you key in your choice, you hit the same Shift key again, the little panel disappears, and you're on your way -- with
alacrity.