He accelerated his mind once again until his vision was in slow motion and search for a gap he could attack from.
However, in this slowed-down scene, the cannons’ firing speed hadn’t decreased as much as the speed of everything around it. It was out of pace. Mismatched.
He knew from Flat’s knowledge that one anti-aircraft gun can normally fire 12 shots per minute, but those were getting gradually faster than that.
“They’re... accelerating?”
The 8 anti-aircraft guns had reached the pace of 1 shot per second.
The advantage provided by the boy’s thought acceleration was being mitigated by the unfair power of a Servant’s Noble Phantasm.

Fate/Strange Fake, Volume 7; Chapter 21 (Beings Shaped In Man's Image)