Benchmarks comparing the PS4 Jaguar CPU to the PS5 Zen CPU show what a massive upgrade the PS5 is for devs, they had regularly expressed frustration at last gen's weak CPU capability
We upgraded PS4 Pro with an 8TB SSD: can we make a better console? | Eurogamer.net
PS4: Install an SSD or HHD to speed up game loading time by 20 seconds or more - ExtremeTech