Measured cold on the 4-vCPU CI VM: CARGO_BUILD_JOBS=4 finishes the workspace test in 392 s against 589 s at jobs=2, with a 2.7 GB peak on a 10 GB guest. The throttle protected a 30 GB rustc that no longer exists in this graph. Leave the job count to cargo in the workflow and in scripts/cargo-test.sh alike; --no-fail-fast and the 20-minute limit stay. cc