diff --git a/.github/workflows/build-tarball.yml b/.github/workflows/build-tarball.yml
index b3a1168d69a4c5..876f6c842e10e0 100644
--- a/.github/workflows/build-tarball.yml
+++ b/.github/workflows/build-tarball.yml
@@ -102,9 +102,9 @@ jobs:
     needs: build-tarball
     runs-on: ubuntu-24.04
     env:
-      CC: sccache clang-19
-      CXX: sccache clang++-19
-      SCCACHE_GHA_ENABLED: 'true'
+      CC: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang-19' || 'clang-19' }}
+      CXX: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang++-19' || 'clang++-19' }}
+      SCCACHE_GHA_ENABLED: ${{ github.base_ref == 'main' || github.ref_name == 'main' }}
       SCCACHE_IDLE_TIMEOUT: '0'
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
@@ -122,6 +122,7 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
           allow-prereleases: true
       - name: Set up sccache
+        if: github.base_ref == 'main' || github.ref_name == 'main'
         uses: Mozilla-Actions/sccache-action@7d986dd989559c6ecdb630a3fd2557667be217ad  # v0.0.9
         with:
           version: v0.12.0
diff --git a/.github/workflows/coverage-linux-without-intl.yml b/.github/workflows/coverage-linux-without-intl.yml
index 25445b760ad9f4..9f2e5000457bb1 100644
--- a/.github/workflows/coverage-linux-without-intl.yml
+++ b/.github/workflows/coverage-linux-without-intl.yml
@@ -37,9 +37,9 @@ env:
   PYTHON_VERSION: '3.14'
   FLAKY_TESTS: keep_retrying
   CLANG_VERSION: '19'
-  CC: sccache clang-19
-  CXX: sccache clang++-19
-  SCCACHE_GHA_ENABLED: 'true'
+  CC: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang-19' || 'clang-19' }}
+  CXX: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang++-19' || 'clang++-19' }}
+  SCCACHE_GHA_ENABLED: ${{ github.base_ref == 'main' || github.ref_name == 'main' }}
   SCCACHE_IDLE_TIMEOUT: '0'
 
 permissions:
@@ -63,6 +63,7 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
           allow-prereleases: true
       - name: Set up sccache
+        if: github.base_ref == 'main' || github.ref_name == 'main'
         uses: Mozilla-Actions/sccache-action@7d986dd989559c6ecdb630a3fd2557667be217ad  # v0.0.9
         with:
           version: v0.12.0
diff --git a/.github/workflows/coverage-linux.yml b/.github/workflows/coverage-linux.yml
index d2495ef60c3ef2..f6184b360f497a 100644
--- a/.github/workflows/coverage-linux.yml
+++ b/.github/workflows/coverage-linux.yml
@@ -37,9 +37,9 @@ env:
   PYTHON_VERSION: '3.14'
   FLAKY_TESTS: keep_retrying
   CLANG_VERSION: '19'
-  CC: sccache clang-19
-  CXX: sccache clang++-19
-  SCCACHE_GHA_ENABLED: 'true'
+  CC: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang-19' || 'clang-19' }}
+  CXX: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang++-19' || 'clang++-19' }}
+  SCCACHE_GHA_ENABLED: ${{ github.base_ref == 'main' || github.ref_name == 'main' }}
   SCCACHE_IDLE_TIMEOUT: '0'
 
 permissions:
@@ -63,6 +63,7 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
           allow-prereleases: true
       - name: Set up sccache
+        if: github.base_ref == 'main' || github.ref_name == 'main'
         uses: Mozilla-Actions/sccache-action@7d986dd989559c6ecdb630a3fd2557667be217ad  # v0.0.9
         with:
           version: v0.12.0
diff --git a/.github/workflows/test-internet.yml b/.github/workflows/test-internet.yml
index bda70922bc5e0d..7e30b846906047 100644
--- a/.github/workflows/test-internet.yml
+++ b/.github/workflows/test-internet.yml
@@ -34,9 +34,9 @@ env:
   PYTHON_VERSION: '3.14'
   FLAKY_TESTS: keep_retrying
   CLANG_VERSION: '19'
-  CC: sccache clang-19
-  CXX: sccache clang++-19
-  SCCACHE_GHA_ENABLED: 'true'
+  CC: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang-19' || 'clang-19' }}
+  CXX: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang++-19' || 'clang++-19' }}
+  SCCACHE_GHA_ENABLED: ${{ github.base_ref == 'main' || github.ref_name == 'main' }}
   SCCACHE_IDLE_TIMEOUT: '0'
 
 permissions:
@@ -60,6 +60,7 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
           allow-prereleases: true
       - name: Set up sccache
+        if: github.base_ref == 'main' || github.ref_name == 'main'
         uses: Mozilla-Actions/sccache-action@7d986dd989559c6ecdb630a3fd2557667be217ad  # v0.0.9
         with:
           version: v0.12.0
diff --git a/.github/workflows/test-linux.yml b/.github/workflows/test-linux.yml
index 1e74796563f27d..fe2a1f9a7d792d 100644
--- a/.github/workflows/test-linux.yml
+++ b/.github/workflows/test-linux.yml
@@ -34,9 +34,9 @@ env:
   PYTHON_VERSION: '3.14'
   FLAKY_TESTS: keep_retrying
   CLANG_VERSION: '19'
-  CC: sccache clang-19
-  CXX: sccache clang++-19
-  SCCACHE_GHA_ENABLED: 'true'
+  CC: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang-19' || 'clang-19' }}
+  CXX: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache clang++-19' || 'clang++-19' }}
+  SCCACHE_GHA_ENABLED: ${{ github.base_ref == 'main' || github.ref_name == 'main' }}
   SCCACHE_IDLE_TIMEOUT: '0'
   RUSTC_VERSION: '1.82'
 
@@ -70,6 +70,7 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
           allow-prereleases: true
       - name: Set up sccache
+        if: github.base_ref == 'main' || github.ref_name == 'main'
         uses: Mozilla-Actions/sccache-action@7d986dd989559c6ecdb630a3fd2557667be217ad  # v0.0.9
         with:
           version: v0.12.0
diff --git a/.github/workflows/test-macos.yml b/.github/workflows/test-macos.yml
index 3920b9a365ebae..ee85e1ea8418da 100644
--- a/.github/workflows/test-macos.yml
+++ b/.github/workflows/test-macos.yml
@@ -80,9 +80,9 @@ jobs:
       fail-fast: false
     runs-on: macos-15
     env:
-      CC: sccache gcc
-      CXX: sccache g++
-      SCCACHE_GHA_ENABLED: 'true'
+      CC: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache gcc' || 'gcc' }}
+      CXX: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache g++' || 'g++' }}
+      SCCACHE_GHA_ENABLED: ${{ github.base_ref == 'main' || github.ref_name == 'main' }}
       SCCACHE_IDLE_TIMEOUT: '0'
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
@@ -101,6 +101,7 @@ jobs:
           rustup override set "$RUSTC_VERSION"
           rustup --version
       - name: Set up sccache
+        if: github.base_ref == 'main' || github.ref_name == 'main'
         uses: Mozilla-Actions/sccache-action@7d986dd989559c6ecdb630a3fd2557667be217ad  # v0.0.9
         with:
           version: v0.12.0
diff --git a/.github/workflows/test-shared.yml b/.github/workflows/test-shared.yml
index 7f92b98929b8be..902b71e13f1a30 100644
--- a/.github/workflows/test-shared.yml
+++ b/.github/workflows/test-shared.yml
@@ -175,6 +175,7 @@ jobs:
           authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
 
       - name: Configure sccache
+        if: github.base_ref == 'main' || github.ref_name == 'main'
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd  # v8.0.0
         with:
           script: |
@@ -195,9 +196,9 @@ jobs:
           nix-shell \
             -I nixpkgs=./tools/nix/pkgs.nix \
             --pure --keep TAR_DIR --keep FLAKY_TESTS \
-            --keep SCCACHE_GHA_VERSION --keep ACTIONS_CACHE_SERVICE_V2 --keep ACTIONS_RESULTS_URL --keep ACTIONS_RUNTIME_TOKEN \
+            ${{ (github.base_ref == 'main' || github.ref_name == 'main') && '--keep SCCACHE_GHA_VERSION --keep ACTIONS_CACHE_SERVICE_V2 --keep ACTIONS_RESULTS_URL --keep ACTIONS_RUNTIME_TOKEN' || '' }} \
             --arg loadJSBuiltinsDynamically false \
-            --arg ccache '(import <nixpkgs> {}).sccache' \
+            ${{ (github.base_ref == 'main' || github.ref_name == 'main') && '--arg ccache ''(import <nixpkgs> {}).sccache''' || '' }} \
             --arg devTools '[]' \
             --arg benchmarkTools '[]' \
             ${{ endsWith(matrix.system, '-darwin') && '--arg withAmaro false --arg withLief false --arg withSQLite false --arg extraConfigFlags ''["--without-inspector" "--without-node-options"]'' \' || '\' }}