diff --git a/.circleci/config.yml b/.circleci/config.yml
index 2127e18be3..9cfe741ce6 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -16,7 +16,7 @@ jobs:
 
     machine:
       image: ubuntu-2204:current
-    resource_class: arm.medium  # two vCPUs
+    resource_class: arm.large  # 4 vCPUs
 
     environment:
       CIBW_ARCHS: "aarch64"
diff --git a/pyproject.toml b/pyproject.toml
index a69720739b..cec96b76b0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,7 +18,7 @@ build-backend = "setuptools.build_meta"
 write_to = "cwltool/_version.py"
 
 [tool.cibuildwheel]
-test-command = "python -m pytest -n 2 --junitxml={project}/test-results/junit_$(python -V | awk '{print $2}')_${AUDITWHEEL_PLAT}.xml -k 'not (test_bioconda or test_env_filtering or test_udocker)' --pyargs cwltool"
+test-command = "python -m pytest --ignore cwltool/schemas -n logical --dist worksteal --junitxml={project}/test-results/junit_$(python -V | awk '{print $2}')_${AUDITWHEEL_PLAT}.xml -k 'not (test_bioconda or test_env_filtering or test_udocker)' --pyargs cwltool"
 test-requires = "-r test-requirements.txt"
 test-extras = "deps"
 skip = "pp*"