diff --git a/.github/workflows/_pr-test-stage-cpu.yml b/.github/workflows/_pr-test-stage-cpu.yml
index 0972a2cc6..889035f58 100644
--- a/.github/workflows/_pr-test-stage-cpu.yml
+++ b/.github/workflows/_pr-test-stage-cpu.yml
@@ -62,7 +62,12 @@ jobs:
     steps:
       - name: Free disk space
         run: |
-          sudo rm -rf /usr/share/dotnet /usr/local/lib/android /opt/ghc
+          # The image ships ~65G free and the suite peaks around 30G; deleting
+          # these trees is ~1M unlinks (~80s), so only pay it when actually low.
+          avail_gb=$(df --output=avail -BG / | tail -1 | tr -dc '0-9')
+          if [ "${avail_gb}" -lt 40 ]; then
+              sudo rm -rf /usr/share/dotnet /usr/local/lib/android /opt/ghc
+          fi
           df -h
 
       - name: Checkout code
diff --git a/.github/workflows/rerun-test.yml b/.github/workflows/rerun-test.yml
index f188c0695..13f5b15a3 100644
--- a/.github/workflows/rerun-test.yml
+++ b/.github/workflows/rerun-test.yml
@@ -245,7 +245,12 @@ jobs:
     steps:
       - name: Free disk space
         run: |
-          sudo rm -rf /usr/share/dotnet /usr/local/lib/android /opt/ghc
+          # The image ships ~65G free and the suite peaks around 30G; deleting
+          # these trees is ~1M unlinks (~80s), so only pay it when actually low.
+          avail_gb=$(df --output=avail -BG / | tail -1 | tr -dc '0-9')
+          if [ "${avail_gb}" -lt 40 ]; then
+              sudo rm -rf /usr/share/dotnet /usr/local/lib/android /opt/ghc
+          fi
           df -h
 
       - name: Checkout code