I did some simple testing to check the straight line speeds of different ships from different factions. Method was simple
1; Start at the most forward part of the spawning zone
2; End at the edge of the map on the enemy side
3; Use the in game timer
4; Boost/Rush/Etc as optimally as you can.

Results;
Avenger, IN, Reload (160 Speed) 3:20~(This includes the combustion boost from the execution command)
Executor, Chaos, Reload (160 speed) 3:45~
Slaughter, Chaos, Reload (240 Speed) 2:20~
Dying Sun, Drukhari, Reload (240 Speed) 2:25~2:30
Vaul, Corsair, Runic (280 Speed) 2:25~
Vaul, Corsair, Reload (280 Speed) 2:20~ (Due to the timing, your last boost comes off cooldown right as you reach the finish line, So this probably deserves to be a little lower)
Killa, Ork, Reload, No Red Paint (160 Speed) 4:10~
Killa, Ork, Reload, Red Paint (160 Speed) 3:25~
Space Marine, Cruiser MKII, Reload (200 Speed) 2:50~
Tau Protector, Custodian, Reload, Experimental Manifolds (185 Speed) 3:05~
Tyrannids, Corrosive Clutch Devourer, Reload (160 Speed) 3:30~3:35
Necron, Cairn, Reload (160 Speed) 3:05~3:10
Necron, Scythe Reaper, Reload (200 Speed) 3:05~3:10 (Due to the timing, your last teleport comes off cooldown right as you reach the finish line, So this deserves to be lower. 5-10ish seconds probably)
Necron, Cartouche, Reload (240 Speed) 2:40

And a imgur gallery link with finish line snap shots; https://imgur.com/a/e9W1J06

Interesting to see a kite faction like Chaos only being quicker than Ork ships that aren't painted red.

@bosie

200 speed chaos ship would take 2:50.

You don’t miss any occasion to make chaos looks worse than it is...

For nids did you use double rush?

@canardnoir I was looking at the 160 ships.

@bosie

Yeah I get it but you said "the chaos faction is only quicker than orks". It sound a lot like a statement for the hole faction and not just GC/BS.

@Bosie
I also put the slaughter in the imgur gallery, but forgot to add it in text! Ive amended this, and the slaughter counts out to 2:20~ Which is the fastest thing on this list, and either as fast or faster then Eldar.

Chaos 160 are slow, but most of Chaos is 200. So you want to look at the Cruiser MkII test for that (2:50)