This question already has an answer here:
I understand that Boba Fett could have worked out the Falcon's destination from it's bearing/trajectory, but if the Falcon is "the fastest hunk of junk in the galaxy", how did Vader manage to "Arrive just before [they] did"?
This implies Vader beat the Falcon to Bespin, doesn't it? how would he have been able to negotiate the terms of the bounty with Boba, and then still beat the ship to Bespin?
Unless by "they" (as in "they arrived just before you did"), Lando is referring to the Empire as an entity, and not to they physical presence of the Empire as Manifest by Vader?
Anyone have any canon answer?