There is an obvious answer, but I figured you weren't talking about the cheat for teleporting a ship. Moving on...
Hard to pull off, but the UP proposal to move ships on war declaration and the nearest ZOC is next to their star thanks to influence bases. Nope, not something you'd be able to use often. Also, doesn't require a fleet.
Also good, and not too hard to pull off, but it'd be difficult to get it to the exact tile necessary to blow it up on the same turn. In any case, the method I'm talking about could theoretically be used every single turn.
I don't remember the event doubling speed, but it's been a very long time since I've had it. I think it was 50%. From what little I remember off of the top of my head, that should be enough to make DA/TA equivalent to DL in terms of speed-possibly slightly more.
With a 24 starbase military array, and +2 speed from each, we're at +48 speed. With the hyperion shrinkers from 9 other races and our own, we can achieve 100% miniaturization from research, 150% from shrinkers, for a total of 250% miniaturization or a total of 555 space on a huge hull, which lets us fit 16 stellar folders in for +96 speed (with 14 space left).
2 (TA base) + 3 (Impulse, Warp, Hyperwarp) + 2 (customization points) + 1 (Terrans) + 1 (hyperion shipyard) + 1 (innovation complex) + 1 (Hyperion Propulsion from Thalans) + 2 (Arcean speed techs) + 2 (Adv Nav center from Arceans) + 96 (16 stellar folders) + 48 (24x MSA) = 159. Add 50% to that and you'll get 238 due to truncation.
(DL would be 275% miniaturization x 80 space for 300 space at 9 space each or 33 hyperwarp III's for 198 speed plus 1 base, 3 from techs, 2 from points, 1 from hyperion shipyard, 48 from the MSA for a total of 253.)
So of course I've neglected minor races building hyperion shrinkers, and if you can get all 8 of them to build them then the numbers are as follows: 370% miniaturization for TA, 395% for DL (using Yor) for 705 space in TA/396 space in DL, with 22x6=132 or 36 more speed in TA as opposed to 44x6=264 or 66 more speed in DL.
Final numbers thanks to minor races would be 195 before the mega event and 292 after for TA, whereas it would be 319 for DL.
So I suppose I've proved myself wrong.
But-neither one of those is 22x15 (immense for the 22, parsecs in sectors for the 15, diagonally) --> 330 parsecs. Well, all right, 329, if you count the one you start on, and of course the star's never going to be exactly in the corner, but you get the idea.
Perhaps I should just say that even if we had a 100x100 sector galaxy I could still cross it in a single turn. 1500 speed, anyone?