diff --git a/.circleci/config.yml b/.circleci/config.yml
index 288749974..826c04785 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -407,8 +407,11 @@ jobs:
       - persist_to_workspace: *artifacts_executables
 
   b_ubu: &build_ubuntu2004
+    resource_class: xlarge
     docker:
       - image: ethereum/solidity-buildpack-deps:ubuntu2004-<< pipeline.parameters.ubuntu-2004-docker-image-rev >>
+    environment:
+      MAKEFLAGS: -j 10
     steps:
       - checkout
       - run: *run_build
@@ -583,9 +586,11 @@ jobs:
       - store_artifacts: *artifacts_test_results
 
   b_ems:
+    resource_class: xlarge
     docker:
       - image: ethereum/solidity-buildpack-deps:emsdk-1.39.15-2
     environment:
+      MAKEFLAGS: -j 10
       TERM: xterm
     steps:
       - checkout
diff --git a/.travis.yml b/.travis.yml
index ef7832777..e20a4d202 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -47,6 +47,7 @@ env:
         - SOLC_TESTS=On
         - SOLC_STOREBYTECODE=Off
         - SOLC_DOCKER=Off
+        - MAKEFLAGS="-j 4"
 
 matrix:
     include:
diff --git a/scripts/ci/build.sh b/scripts/ci/build.sh
index 1c8824abf..a939412f6 100755
--- a/scripts/ci/build.sh
+++ b/scripts/ci/build.sh
@@ -20,4 +20,4 @@ cd build
 # shellcheck disable=SC2086
 cmake .. -DCMAKE_BUILD_TYPE="${CMAKE_BUILD_TYPE:-Release}" $CMAKE_OPTIONS -G "Unix Makefiles"
 
-make -j 4
+make
diff --git a/scripts/travis-emscripten/build_emscripten.sh b/scripts/travis-emscripten/build_emscripten.sh
index 5c7e3f052..3162e13b6 100755
--- a/scripts/travis-emscripten/build_emscripten.sh
+++ b/scripts/travis-emscripten/build_emscripten.sh
@@ -53,7 +53,7 @@ cmake \
   -DBoost_USE_STATIC_RUNTIME=1 \
   -DTESTS=0 \
   ..
-make -j 4 soljson
+make soljson
 # Patch soljson.js for backwards compatibility.
 # TODO: remove this with 0.7.
 # "viiiii" encodes the signature of the callback function.