Tests with S3 stubber run slower while connected to the internet

[hugochinchilla]

I have a test suite that runs in 27 seconds while connected to the internet but only 1.3 seconds while offline.

Online:
pytest tests/summit/test_downloads.py 1.27s user 0.88s system 7% cpu 27.478 total

Offline:
pytest tests/summit/test_downloads.py 1.27s user 0.80s system 154% cpu 1.349 total

From the profiler I think the culprit is here:

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
       ...
       26    0.001    0.000   26.027    1.001 connection.py:27(create_connection)
       26   26.023    1.001   26.023    1.001 {method 'connect' of '_socket.socket' objects}
       13    0.000    0.000   13.024    1.002 utils.py:448(_fetch_metadata_token)
       ...

It looks like is trying to establish some kind of connection and timeing out after 1 second before sticking to the stubber.
I would appreciate any help to solve this.