Hm, let's see if just caching half the virtualenv will work.

.travis.yml

@@ -1,12 +1,9 @@
 language: python
 python:
   - "3.3"
-before_install:
-  - "sudo add-apt-repository -y ppa:fkrull/deadsnakes"
-  - "sudo apt-get -y update"
-  - "sudo apt-get -qq install python3.3 python3.3-dev python3-sphinx"
-  - "virtualenv -p /usr/bin/python3.3 ~/virtualenvs/3.3_debian"
-  - "source ~/virtualenvs/3.3_debian/bin/activate"
+cache:
+  directories:
+    - /home/travis/virtualenv/python3.3.5/lib/python3.3/site-packages
 install:
   - "pip install -r dev-requirements.txt"
 script: