While switching configurations I've came across this issue yet again and I believe I have a workaround for this if you're still interested.
The steps I do to reproduce:
start fresh emacs,
venv-workon to activate a virtualenv,
open a python buffer,
try elpy-goto-definition, receive the same error message you did.
(elpy-config confirms everything is ok)
It is caused due to common * syntax of lists and italics. For deeply nested lists, parsing gets expensive due to recursive checks for italics. If you are willing to abandon *italics* syntax in favor of _italics_ then the computational overhead can be avoided.
"\\(?:^\\|[^\\]\\)\\(?1:\\(?2:[_]\\)\\(?3:[^ \n\t\\]\\|[^ \...