Things do slow down in space due to the absence of gravity and friction.
Another reason things slow down in space is due to the natural vacuum that is present in space that is not present here on earth.
Time also seems to slow down in space as a result of things moving more slowly in space than they do here on earth.
Time slows down or speeds up depending on how fast you move relative to something else however time is still going the same speed although it seems like it's speeding up or slowing down.
So it only seems that time is slower in space but it's actually going at the exact same speed as it does here on earth.
There's now way to actually speed up time or slow down time.