diff --git a/.github/workflows/L1-tests.yml b/.github/workflows/L1-tests.yml
index 9cc944c138..6597e6a947 100755
--- a/.github/workflows/L1-tests.yml
+++ b/.github/workflows/L1-tests.yml
@@ -28,6 +28,34 @@ jobs:
             coverage: without-coverage
 
     steps:
+        - name: Set up cache
+        # Cache Thunder/ThunderInterfaces.
+        # https://github.com/actions/cache
+        # https://docs.github.com/en/rest/actions/cache
+        # Modify the key if changing the list.
+        if: ${{ !env.ACT }}
+        id: cache
+        uses: actions/cache@v3
+        with:
+          path: |
+            build/Thunder
+            build/ThunderTools
+            install
+            !install/etc/WPEFramework/plugins
+            !install/usr/bin/RdkServicesL1Test
+            !install/usr/include/gmock
+            !install/usr/include/gtest
+            !install/usr/lib/libgmockd.a
+            !install/usr/lib/libgmock_maind.a
+            !install/usr/lib/libgtestd.a
+            !install/usr/lib/libgtest_maind.a
+            !install/usr/lib/cmake/GTest
+            !install/usr/lib/pkgconfig/gmock.pc
+            !install/usr/lib/pkgconfig/gmock_main.pc
+            !install/usr/lib/pkgconfig/gtest.pc
+            !install/usr/lib/pkgconfig/gtest_main.pc
+            !install/usr/lib/wpeframework/plugins
+          key: ${{ runner.os }}-${{ env.THUNDER_REF }}-${{ env.INTERFACES_REF }}-4
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
@@ -61,18 +89,15 @@ jobs:
             sudo ninja -C build install
 
       - name: Checkout Thunder
+        if: steps.cache.outputs.cache-hit != 'true'
         uses: actions/checkout@v3
         with:
           repository: rdkcentral/Thunder
           path: Thunder
           ref: ${{env.THUNDER_REF}}
 
-      - name: Checkout rdkservices
-        uses: actions/checkout@v3
-        with:
-          path: rdkservices
-
       - name: Build Thunder
+        if: steps.cache.outputs.cache-hit != 'true'
         run: >
           cmake
           -S "${{github.workspace}}/Thunder/Tools"
@@ -100,6 +125,11 @@ jobs:
           &&
           cmake --install build/Thunder
 
+      - name: Checkout rdkservices
+        uses: actions/checkout@v3
+        with:
+          path: rdkservices
+
       - name: Checkout ThunderInterfaces
         uses: actions/checkout@v3
         with: