Gee my windows is out of date!

[Me+Me]

Oh you mean that it will take less time for the update to install and after restart for it to be back where it was again. I don't doubt it.

But for actually installing the update, it shouldn't make any difference if it is a HDD or SSD, it is just a storage device, just binary code.

it does if the hdd has faults, bad sectors etc.   One of the more obscure failings of hdds I see is unusually high average response time (from task manager) should be 10ms or less but in this failing scenario they can be in excess of 10000ms ie 10 seconds for a single data request...

The clue is in the 6 hours - that is way too long for a feature update, something is wrong, my guess is hardware.  If it was a software or windows kinda fault that process (including reverting ) would only take an hour or so...

Agree - perhaps run Hdd Sentinal, (free edition), it only takes a couple seconds to report.