--- a/taskcluster/ci/test/test-platforms.yml
+++ b/taskcluster/ci/test/test-platforms.yml
@@ -18,16 +18,17 @@
 linux32/debug:
     build-platform: linux/debug
     test-sets:
         - linux32-tests
 linux32/opt:
     build-platform: linux/opt
     test-sets:
         -  linux32-tests
+        -  linux32-opt-tests
 
 linux64/debug:
     build-platform: linux64/debug
     test-sets:
         - common-tests
         - external-media-tests
         - web-platform-tests
 linux64/opt:

--- a/taskcluster/ci/test/test-sets.yml
+++ b/taskcluster/ci/test/test-sets.yml
@@ -161,25 +161,28 @@ linux32-tests:
     - jittest
     - jsreftest
     - marionette
     - mochitest
     - mochitest-a11y
     - mochitest-browser-chrome
     - mochitest-chrome
     - mochitest-clipboard
-    - mochitest-devtools-chrome
     - mochitest-gpu
     - mochitest-jetpack
     - mochitest-media
     - mochitest-webgl
     - web-platform-tests
     - web-platform-tests-reftests
     - xpcshell
 
+linux32-opt-tests:
+    # mochitest-dt is too slow on linux32/debug
+    - mochitest-devtools-chrome
+
 android-common-tests:
     - cppunit
     - crashtest
     - jsreftest
     - mochitest
     - mochitest-chrome
     - mochitest-clipboard
     - mochitest-gpu