What changed in 6.0 that makes the "wipe cache partition" command so slow?

[Crashdamage]

The correct question is why the hell is it necessary to manually delete the cache partition in the first place, and why the hell do people still tolerate it? After the pile of hot garbage that is Lollipop, it would seem Google would try to make Android better. Nope.

That is not the correct question. The correct question is why so many users do it needlessly. It's not "necessary to manually delete the cache partition". It's not even recommended unless you're having problems that could be related to cache files. Android is quite capable of taking care of business if users will just let it. And I found Lollipop to be a nice step forward in the evolution of Android.