try using latest LLVM instead of tot to see effect on testing time
diff --git a/.circleci/config.yml b/.circleci/config.yml
index 7751604..d3f4c1f 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -139,8 +139,8 @@
             tar -C ~ -xf ~/emsdk-main.tar.gz
             mv ~/emsdk-main ~/emsdk
             cd ~/emsdk
-            ./emsdk install tot
-            ./emsdk activate tot
+            ./emsdk install latest
+            ./emsdk activate latest
             # Remove the emsdk version of emscripten to save space in the
             # persistent workspace and to avoid any confusion with the version
             # we are trying to test.