I'm sure someone will give a "speed of plot" answer. It's not very satisfying, but unfortunately there is no good rational way to explain any of it, and "speed of plot" is probably the most-canon answer there is.
Well, we can sort of guesstimate from what we see in TPM. Consider how long it takes Maul to get from Courscant to Tatooine - we see him talking to his Boss, the events of one day unfold (perhaps two - I don't remember clearly if there was a couple of nights in there), Maul arrives at dawn.
Now, Palpatine probably provided him with the most tricked out ride in the known universe, so that's most likely the absolutely fastest the trip can be made. Double that time (minimum) for a bog standard x1 drive. and 4x times that for a x2.
Since Tatooine and Bespin are more or less the same distance - but not on a major hyperspace lane - you wouldn't be too far off if you said 5 days for a x1 hyperdrive (up or down, depending on their astrogation rolls, of course).
Oddly enough, write-ups for the Scimitar (Sith Infiltrator) give it a hyperdrive with anywhere from a Class 1.5 (Wookieepedia) to Class 3 (ESsential Guide to Vehicles & Vessels).
I don't use the travel times from the Prequels as they allow for crossing the galaxy in absurdly short periods of time (even for Star Wars) that don't even come close to matching what's in the Edge of the Empire book. And yes, for the purposes of the game, I consider the FFG materials more 'canon' than any other materials, including the films.