diff --git a/tox.ini b/tox.ini
index 10120691..80481da7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -37,11 +37,11 @@ basepython =
 
 [testenv:apicheck]
 commands = pip install -U -r{toxinidir}/requirements/dev.txt
-    sphinx-build -b apicheck -d {envtmpdir}/doctrees docs docs/_build/apicheck
+    sphinx-build -j2 -b apicheck -d {envtmpdir}/doctrees docs docs/_build/apicheck
 
 [testenv:linkcheck]
 commands = pip install -U -r{toxinidir}/requirements/dev.txt
-    sphinx-build -W -b linkcheck -d {envtmpdir}/doctrees docs docs/_build/linkcheck
+    sphinx-build -j2 -W -b linkcheck -d {envtmpdir}/doctrees docs docs/_build/linkcheck
 
 [testenv:flake8]
 commands =