Comment by vel0city

I wonder how much of that is the software demands increasing and the flash storage itself wearing out over time. As flash storage wears it'll often go slower and slower as the error correction needs to process more to actually get you the uncorrupted bits. This is why a lot of cheap devices tend to just become unbearably slow after a while, their storage just gets to be way too slow.

Flash storage doesn't last forever, and it's got a whole gradient of failure and wear experiences.