1. Exact behavior is that Emacs freezes for about a minute and displays (in bold) in the type of the word I'm over.

    Thus, I was trying to edit a small a-list with dummy 0.000s in the range.  Every third keystroke, emacs stopped to tell me that

    my cursor was over 0.000::Double and I have to wait an indeterminate time (at least tens of seconds, sometimes a minute or more)

    to get control back.

So, the underlying mechanism to determine type at current cursor position isn't very fast. In spacemacs+intero C-c C-t (or C-c C-i) takes anywhere between 1 to 10 sec for me. Something in your setup has made this lookup automatic. It's trying to determine the type as your browse around your source code. Do you have any idea what could have caused that?

You could try one more thing. Try delivering a SIGUSR2 to the Emacs process when it's stuck. It will stop doing whatever is holding it up and drop you into some sort of a debugger. That can give you some clues about what is causing this behaviour in your setup.

-- Saurabh.