Space for a time.
As supra-light things slow down their mass increases, their energy increases, and it becomes impossible to slow them that last tiny bit.
The Machine
The machine is a fire-bred monster, which roars as it works, never sleeps, never stops, never thinks twice about slowing down, watch as it works.
Future Sanctuary - Chapter 1: Fireball
The felinoid male bows again, "it does not appear to be a natural object, it is slowing and our black skyships reported it came from out of the system at extreme speed, slowing significantly with a bright flash before it entered the atmosphere."
Writing Advice: Show, Tell, Adverbs and Others
So the advantage of 'telling' is that you can summarize details that slow things down too much, preventing your story getting bogged down in unnecessary detail.
Blood on Ice - Chapter Seven
I could not stop or slow down, or else i'd risk being claimed by the storm. i dragged my hindpaws, willing them to keep moving forward but my strength was nearly depleted. i kept glancing at midnight to see if he was showing signs of slowing down.
The Truth
He fills the river with more blood and i scramble to slow it down. i lost my friends to the river and to him. i fight day in and day out to slow down a river that no one notices. i cannot give up, i pledged an oath to them.
Titania's Song And Dance
My movement becoming slow and one of mourning. the rain picks up, but my song can still be heard. the rain dares not to drown the feeling, emotion, and meaning behind my words.
WOLVES MIST - Chapter 1(.2)
Once again his mind slowed in numbness and sleep overcame him.
LoS: A New Age Chapter 5
._ he didn't have much time to think this so he had to slow down considerably. he then sped up again and as he assumed she went down. he rocketed towards her but he wasn't using his wings.
Race to live prt.4
Venom had a good three car lengths ahead of me, it was going to take some hard pushen to catch up to her, venom started to slow down for the first turn, and from what i saw, she wasn't slowing down enough, but sure enough, she took the turn hard
Eddie's Pokemon Adventure: The Redemption
"slow down a bit, we're close." he obeyed me, slowing down greatly as we passed into the route, slowing to a run of human speed. i gazed atop the cliff walls. a very familiar set of grooves in stone caught my eye. "stop!!!"
School Daze: The Story
When we reached the floor, another slow song was playing.