Why would things move slower in space, unfettered by the fascist repression of atmosphere and gravity? In fact, they actually tend to go faster. Since there's a near complete lack of external forces, as long as a spacecraft is firing its thrusters, it's accelerating (up to a certain extent, of course). That's why rocket scientists use the concept of delta-v -- basically saying, "How much fuel are we going to have to burn to pull that s**t off?" Spacecraft are limited not by surrounding forces, but by how much fuel they have left and how tired someone at mission control is of holding down the GO! button.
So why do actual astronauts look like they're constantly pantomiming through peanut butter? It is solely the fault of the astronomical assload of gear they have to wear. You go suit up in an incredibly bulky, insanely expensive spacesuit (you break it, you buy it ... and, uh, you also die), and then see how sprightly you are.
That thing weighs a ton. Well, it weighs nothing, but you know what we mean.
And if you've ever seen video from inside the space station and wondered why everybody looks like they're running in a dream, that's not because quick movements are impossible. They're just not advisable. Jump-kicking across the length of the ISS might sound awesome, but the only thing absorbing all that force when you reach the other side is your own squish-filled meatsack. Even if you survive unscathed, all of that seriously expensive and utterly vital equipment is now smashed to bits.
The slow movements you see in real space footage aren't the astronauts wading through some weird, invisible space jam; it's simply them being very, very careful. But we're pretty sure every astronaut has jump-kicked across the ISS at least once, just to get it out of their system.
Related Reading: Did you know space holds a gigantic liquor cabinet big enough for God? And were you aware that Zambia had a space agency? The story is more ridiculous than you can imagine. We've got crazier stories than that, though -- check out the most badass things ever done in space.