They're traveling in a medium, so they move slower than in space
Due to the random walk caused by multiple scattering, it can take millions of years for a photon to escape the sun after bring produced in the core.
You are right that they don't gather energy, but they do multiply. What would be a single high energy x ray in the core will eventually downscatter into an army of optical photons.
For photons, their moving relatively slow from the inside to the outside of the sun. Although, I think, it's technically a bunch of photons bumping each other into existence.
... they definitely don't move slowly through the sun.
They kind of do. While the photons inside the Sun move at a very high speed, they can take up to about 170,000 years to get from the middle of the Sun to the outside, because they change directions a lot on the way.
From the perspective of the photon, this all happens more or less instantaneously. Or so I have been told. I was also told that my tongue has 5 or 6 zones where different aspects of flavor are detected and I now know that to be wrong. So maybe fuck your ice cream.
That's relativity. The faster a thing goes the slower time runs for them. Photons are travelling at light speed and so they don't experience time at all
photons are generated at the core from matter by hydrogen fusion (bigger elements later in the star life), the photons travel to the surface by absorption and re-emission taking about 100,000 years in average to escape, despite traveling at the speed of light. so the slow part depends on perspective
“It took me a hundred thousand years to escape the prison of a motherfucking star, and you have the gall to complain about your little ice cream cone melting?!