For the startup time, you could keep it around as builtin but save the import time until someone actually uses it.
While I agree sqrt should be a builtin as well, I think there's a good argument to be made for Path to. I just switched to it the past month, and im liking it a lot over constructs like (real code example): os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "filename"). (could probably be inproved by changing to __path__ and removing the dirname ? but the current version works...)
sqrt isn't as much used in situations I've been in - and when it was, I generally got a giant heap of data to process and was doing that with numpy anyway.