diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 73fa11a..e726f23 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -2,6 +2,7 @@ name: Tests
 on: [push]
 
 jobs:
+
   Composer:
     runs-on: ubuntu-latest
     steps:
@@ -11,43 +12,109 @@ jobs:
       run: composer validate
     - name: Install dependencies
       run: composer install --prefer-dist --no-dev
+      
   PHPunit:
     runs-on: ubuntu-latest
     strategy:
       matrix:
         php-versions: ['5.6', '7.0', '7.1', '7.2', '7.3', '7.4']
     name: PHP ${{ matrix.php-versions }} unit tests on ${{ matrix.operating-system }}
+    env:
+      extensions: gd, sqlite3
+      extensions-cache-key-name: phpextensions
+      
     steps:
+    
+    # let's get started!
     - name: Checkout
       uses: actions/checkout@v2
+      
+    # cache PHP extensions
+    - name: Setup cache environment
+      id: extcache
+      uses: shivammathur/cache-extensions@v1
+      with:
+        php-version: ${{ matrix.php-versions }}
+        extensions: ${{ env.extensions }}
+        key: ${{ runner.os }}-${{ env.extensions-cache-key }}
+
+    - name: Cache extensions
+      uses: actions/cache@v2
+      with:
+        path: ${{ steps.extcache.outputs.dir }}
+        key: ${{ steps.extcache.outputs.key }}
+        restore-keys: ${{ runner.os }}-${{ env.extensions-cache-key }}
+      
     - name: Setup PHP
       uses: shivammathur/setup-php@v2
       with:
         php-version: ${{ matrix.php-versions }}
-        extensions: gd, sqlite3
+        extensions: ${{ env.extensions }}
+  
+    # Setup GitHub CI PHP problem matchers
+    # https://github.com/shivammathur/setup-php#problem-matchers
+    - name: Setup problem matchers for PHP
+      run: echo "::add-matcher::${{ runner.tool_cache }}/php.json" 
+    
+    - name: Setup problem matchers for PHPUnit
+      run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
+      
+    # composer cache
     - name: Remove composer lock
       run: rm composer.lock
+      
+    - name: Get composer cache directory
+      id: composer-cache
+      run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+    
+    # http://man7.org/linux/man-pages/man1/date.1.html
+    # https://github.com/actions/cache#creating-a-cache-key
+    - name: Get Date
+      id: get-date
+      run: |
+        echo "::set-output name=date::$(/bin/date -u "+%Y%m%d")"
+      shell: bash
+    
+    - name: Cache dependencies
+      uses: actions/cache@v2
+      with:
+        path: ${{ steps.composer-cache.outputs.dir }}
+        key: ${{ runner.os }}-composer-${{ steps.get-date.outputs.date }}-${{ hashFiles('**/composer.json') }}
+        restore-keys: ${{ runner.os }}-composer-${{ steps.get-date.outputs.date }}-
+    
+    # composer installation
     - name: Setup PHPunit
       run: composer install -n
+
     - name: Install Google Cloud Storage
       run: composer require google/cloud-storage
+    
+    # testing
     - name: Run unit tests
       run: ../vendor/bin/phpunit --no-coverage
       working-directory: tst
+      
   Mocha:
     runs-on: ubuntu-latest
     steps:
+    
     - name: Checkout
       uses: actions/checkout@v2
+      
     - name: Setup Node
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v2
       with:
         node-version: '12'
+        cache: 'npm'
+        cache-dependency-path: 'js/package.json'
+        
     - name: Setup Mocha
       run: npm install -g mocha
+      
     - name: Setup Node modules
       run: npm install
       working-directory: js
+      
     - name: Run unit tests
       run: mocha
       working-directory: js