The problem always with victory conditions is that you can focus down that one path, and ignore everything else. So if you want a culture victory, you really don't need to worry about science, other than unlocking whatever buildings you want to build.
And obviously, since the game has the deep snowball still, if you're finishing every tech in 2-3 turns, it really doesn't take a long time to just bomb down the path to the space race, and finish that off. Especially if you set yourself up enough at the end of the exploration that you're not really worried that the AI will rush the artifacts before you can, or that they will actually be able to war you properly to cause you to shift focus.
They switched up a little on the econ path and the culture paths, and at least now I would say that the 4 paths are all more or less balanced, in that whichever of them you are best suited for, other than some extreme cases, you're probably completing it in that 40-60 turn range if you don't delay too much. But they're still pretty short on the whole.
I don't think just delaying the projects really makes any sense. The game isn't more fun if the banker takes 4 turns to teleport between each capital. You could probably swap around the trees a little bit more to balance. Like if explorers were only unlocked at Hegemony or whatever where currently you can start digging up the earlier eras, at least in any normal gameplay, you're now at least 10-15 civics away before you can even get started on the path, so that should add another 30-40 turns. Similarly you could not give ideology points until you actually picked an ideology, which means warring from turn 1 of the era wouldn't help you down that route. But science all you can do is add more pieces or make things more expensive, realistically. And the Econ path while i do kind of enjoy it now, either you need to completely redesign that, or just again, add in something else to artificially slow it down (limits on factory resource slots or something).