title: Tox takes always 30 seconds to run
body: <p>Tox was running fine a couple of weeks ago, but I've come back to a project which uses tox to run the tests, and now it always takes 30 seconds to run. I thought it could be a problem with changes made to a project, but I've tried tox in other projects (even a hello world test) and they all take 30 seconds to run.</p>
  
  <pre><code>$ time tox
  GLOB sdist-make: /private/tmp/dependency_manager/setup.py
  py27 inst-nodeps: /private/tmp/dependency_manager/.tox/dist/dependencyManager-1.3.6.zip
  py27 installed: boto==2.41.0,boto3==1.3.1,botocore==1.4.33,dependencyManager==1.3.6,docutils==0.12,funcsigs==1.0.2,futures==3.0.5,jmespath==0.9.0,mock==2.0.0,nose2==0.6.5,pbr==1.10.0,python-dateutil==2.5.3,six==1.10.0,troposphere==1.6.0
  py27 runtests: PYTHONHASHSEED='3107006541'
  py27 runtests: commands[0] | nose2
  /private/tmp/dependency_manager/.tox/py27/lib/python2.7/site-packages/troposphere/dynamodb.py:10: UserWarning: This module is outdated and will be replaced with troposphere.dynamodb2. Please see the README for instructions on how to prepare for this change.
    warnings.warn("This module is outdated and will be replaced with "
  .....................
  ----------------------------------------------------------------------
  Ran 21 tests in 0.020s
  
  OK
  _____________________________________________________________________________________________ summary ______________________________________________________________________________________________
    py27: commands succeeded
    congratulations :)
  tox  1,67s user 0,43s system 6% cpu 32,192 total
  </code></pre>
  
  <p>Now a totally different project.</p>
  
  <pre><code>$ time tox
  py27 recreate: /Users/jose.armesto/dev/dredd/.tox/py27
  py27 installdeps: nose, mock, coverage &gt;= 3.3
  py27 installed: coverage==4.1,funcsigs==1.0.2,mock==2.0.0,nose==1.3.7,pbr==1.10.0,six==1.10.0
  py27 runtests: PYTHONHASHSEED='1261821084'
  py27 runtests: commands[0] | nosetests --with-coverage --cover-branches
  ....
  Name                  Stmts   Miss Branch BrPart  Cover
  -------------------------------------------------------
  funcsigs.py             432    357    194      0    12%
  funcsigs/version.py       1      0      0      0   100%
  mock.py                   4      0      0      0   100%
  mock/mock.py           1373    987    578     44    23%
  pbr.py                    0      0      0      0   100%
  pbr/version.py          218    116     66     16    42%
  six.py                  444    218    134     21    46%
  dredd.py                  0      0      0      0   100%
  dredd/discovery.py        0      0      0      0   100%
  dredd/dredd.py           28      0     18      1    98%
  dredd/instance.py         9      1      0      0    89%
  -------------------------------------------------------
  TOTAL                  2509   1679    990     82    28%
  ----------------------------------------------------------------------
  Ran 4 tests in 0.026s
  
  OK
  _____________________________________________________________________________________________ summary ______________________________________________________________________________________________
    py27: commands succeeded
    congratulations :)
  tox  3,67s user 0,87s system 12% cpu 37,636 total
  </code></pre>
  
  <p><strong>It's like something timeouts at 30 seconds</strong>, and then it just run the tests normally.
  I've tried to use <code>ls -lah</code> as command and profile tox, and I got these results <a href="http://pastebin.com/EtQh3Xhq" rel="nofollow">http://pastebin.com/EtQh3Xhq</a>.</p>
  
  <p>I'm running on OSX Yosemite 10.10.5
  Python and tox versions</p>
  
  <pre><code>$ python --version
  Python 2.7.10
  
  $ tox --version
  2.3.1 imported from /Library/Python/2.7/site-packages/tox/__init__.pyc
  </code></pre>
  
  <p>I've tried projects with and without <code>setup.py</code>, with more or less environments, and I always get the same slow time. Anybody knows what's going on and how to fix it?</p>