The unresponsive thing is because the whole explorer.exe still seems to be one big single threaded process. One thing hanging kills everything. Including stuff completely unrelated to the file manager like the task bar. So weird.
This option has existed since win2k IIRC:
Tools > Folder Options > View > Launch folder windows in a separate processed
They're really bad at modernising legacy parts of the OS. Even to this day parts of the old control panel exist and it's been like a decade that they've been working on it.
That is what keeps Windows usable though. I prefer them not the rip the last bits of sanity out.