Build docs in parallel (#1842)

diff --git a/.travis.yml b/.travis.yml
index c4a21499749829c9182b2ac50c128af817ad2805..335fd9fd3d3bfcd05907880ab21c1dd4dcc71644 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -42,7 +42,7 @@ matrix:
         # (Updating the version is fine as long as no warnings are raised by doing so.)
         - python -m pip install sphinx~=1.6.1
       script:
-        - make check suspicious html SPHINXOPTS="-q -W"
+        - make check suspicious html SPHINXOPTS="-q -W -j4"
     - os: linux
       language: c
       compiler: gcc