I don’t understand why it’s the case, but physicists seem to say that no time passes from the perspective of photons. Something to do with the closer you move to the speed of light, the slower time moves from your perspective, and if you’re moving at the speed of light, then you’ve reached the 100% point at which point time is just frozen.

It also seems to be the case that photons would be going faster, if they could, but they’re limited by the speed of causality.
The way I understand that, it’s because we believe photons to have no mass. And taking the classic formula F = m*a and rearranging it for acceleration a = F/m, you suddenly divide by 0, which means if any force is applied, its acceleration should be infinite, which means it should immediately accelerate to infinite speed.

So, I would say it really depends what “slowing down time” means. Is the speed of everything with mass reduced, but the speed of causality stays the same? Or is the speed of causality reduced as well?

Here’s some more info on that whole speed of causality thing: https://www.pbs.org/video/pbs-space-time-speed-light-not-about-light/