Imanex’s least step run is out now and it uses a couple of portal boosts. This got me thinking of something that could cause it.
Considering that Jukspa got a portal boost consistent in a TAS, I’m thinking that they are probably time based. The time at which we achieve a portal boost could be determined when we load a save, or shoot a portal. Probably when we shoot a portal, because EVERY portal boost I have seen have been achieved shortly after the portal is placed. The window of time that we have to achieve a portal boost is still unknown, but it’s probably VERY small considering that we can rarely get portal boosts. If this is true, then I think we could possibly create setups for portal boosts and they might be consistent. If people can get this strat consistent, then we can definitely make some setups for portal boosts.
Another thing to consider is what YaLTeR said.
With this in mind, the distance from portal to portal must affect speed.
Not only speed, but it might also be easier to portal boost when the portals are farther away from each other because the game will have a harder time figuring out where you are and what your speed is.