Have a read of this thread: https://forums.frontier.co.uk/showthread.php?t=151389
Another commander kindly calculated my optimal jump distance for me (994LY). Plotting a route within 2 LY either side of this only took about 5 seconds in the galactic core. It made my life so much easier.
Do this! A little bit of mathematics can save you hours of time plotting. For my 31 Ly range Asp I was able to plot a 984 Ly route in three seconds right out of the core.
Also, it helps to diverge a little bit on the z-axis when leaving, stellar density reduces slightly that way. Since I wanted to go Neutron farming on my way back, I headed out in a 45° angle to the galactic plane. Useful fact to know: going in a 45° angle as in downward and outward, a 1000 Ly diagonal are 700 Ly on both axes. Going 45° as in downward, outward and backward is 577 Ly on each axis.