It takes time to warp himself, however it takes no time at all to go intangible, as I said im comparing overall speed & while naruto can travel short distances in a significant amount of time, obito has multiple other speed feats that make him overall faster.
& I agree obito's speed is next to nothing without kamui
Did you miss the part where kakashi gave naruto a head's up? Did you also miss the two exclamation points indicating extreme surprise??
Obito failed because kakashi saved naruto's ass
He didnt try to grab, but rather strike. Naruto reacted in time due to kakashi's warning.
The scan clearly shows obito covering more distance, he could even get more if not the ground, naruto however is still in flight.
Obito>naruto in speed.
Kakashi giving heads up to Naruto doesn't have anything to do with speed.
Naruto was distracted and exhausted.True he wouldn't have noticed Obito if it wasn't for Kakashi.But that can't characterize him slower than Obit

bito was trying to strike Naruto when he was weak fighting against Juubi.
That panel only proves that Naruto>Obito in speed.
He had time to avoid Obito's hit even though he only noticed seconds before.Obito was already halfway out of kamui dimension and still not fast enough to strike him.And again Naruto only noticed Obito after he was
halfway his jutsu.Obito was unwrapping at that moment,making it clear that Naruto was able to react and move faster even when Obito had already started to move.
In distance travel, it's not wise to compare an S/T user with a regular ninja in speed.I don't even remember a battle when traveling a long distance was must feat to defeat someone.So battle wise,long distance travel is useless.
Also intangibility is not a speed feat.Obito just sends a part of his body to the other dimension.He is not moving that part.Which means that if Obito himself wont move with regular speed that part will only reaper in the exact same spot.To measure speed you need to cover distance in an amount of time.Sending part of his body in kamui dimension isn't movement by itself.Obito needs to move his whole body and then reappear his body members to consider intangibility as movement.