From here.

There was absolutely no delay between the bike stopping and the rider leaping out of it and towards the door. No, he wasn't in a panic, nor in any way running harder than would enable him to do what was needed that she couldn't do herself...

But Bucky was still running pretty hard. He didn't burst through the door (because getting interrupted by worried neighbors was not on the plan), and yet somehow was looming over Natalia in no time at all.