diff --git a/.github/workflows/cleanup-caches.yml b/.github/workflows/cleanup-caches.yml
new file mode 100644
index 000000000..2f666007a
--- /dev/null
+++ b/.github/workflows/cleanup-caches.yml
@@ -0,0 +1,28 @@
+name: Cleanup caches on closed PRs
+# From https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/caching-dependencies-to-speed-up-workflows#matching-a-cache-key
+on:
+  pull_request:
+    types: [ closed ]
+jobs:
+  cleanup:
+    runs-on: ubuntu-latest
+    permissions:
+      actions: write
+    steps:
+      - name: Cleanup
+        run: |
+          echo "Fetching list of cache keys"
+          cacheKeysForPR=$(gh cache list --ref $BRANCH --limit 100 --json id --jq '.[].id')
+
+          ## Setting this to not fail the workflow while deleting cache keys.
+          set +e
+          echo "Deleting caches..."
+          for cacheKey in $cacheKeysForPR
+          do
+              gh cache delete $cacheKey
+          done
+          echo "Done"
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}
+          BRANCH: refs/pull/${{ github.event.pull_request.number }}/merge
diff --git a/.github/workflows/cmake.yml b/.github/workflows/cmake.yml
index 6580569e7..5129fd87d 100644
--- a/.github/workflows/cmake.yml
+++ b/.github/workflows/cmake.yml
@@ -4,6 +4,17 @@ on:
     branches: [ develop ]
   pull_request:
     branches: [ develop ]
+    paths:
+      - .github/workflows/cmake.yml
+      - .gitmodules
+      - '**/CMakeLists.txt'
+      - '**/*.cmake'
+      - '**/*.in'
+      - '**/*.h'
+      - '**/*.c'
+      - '**/*.cc'
+      - '**/*.cpp'
+      - '**/*.f'
 jobs:
   build:
     # See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
@@ -18,6 +29,18 @@ jobs:
         no_mpi: [OFF, ON]
         cxx_standard: [11, 20]
         metis: [OFF, ON]
+        exclude:
+          - compiler: { name: LLVM }
+            build_type: Release
+          - cxx_standard: 20
+            build_type: Release
+    env:
+      CCACHE_DIR: ${{github.workspace}}/.ccache
+      CCACHE_BASEDIR: ${{github.workspace}}
+      CCACHE_COMPRESS: true
+      CCACHE_MAXSIZE: 100M
+      CMAKE_C_COMPILER_LAUNCHER: ccache
+      CMAKE_CXX_COMPILER_LAUNCHER: ccache
 
     steps:
     - uses: actions/checkout@v4
@@ -32,6 +55,31 @@ jobs:
       if: matrix.metis == 'ON'
       run: sudo apt install libmetis-dev
 
+    - name: setup ccache
+      id: setup-ccache
+      run: |
+        sudo apt-get install ccache
+        ccache -p # Print ccache config
+        echo timestamp=$(date -u '+%Y-%m-%dT%T') >> "$GITHUB_OUTPUT"
+
+    - name: ccache
+      uses: actions/cache@v4
+      with:
+        path: ${{github.workspace}}/.ccache
+        key: "${{matrix.compiler.name}}-\
+          cxx:${{matrix.cxx_standard}}-\
+          ${{matrix.build_type}}-\
+          nompi:${{matrix.no_mpi}}-\
+          ccache-${{steps.setup-ccache.outputs.timestamp}}"
+        restore-keys: "${{matrix.compiler.name}}-\
+          cxx:${{matrix.cxx_standard}}-\
+          ${{matrix.build_type}}-\
+          nompi:${{matrix.no_mpi}}-\
+          ccache-"
+
+    - name: Clear ccache statistics
+      run: ccache -z
+
     - name: Configure CMake
       env:
         MPICH_CXX: ${{matrix.compiler.CXX}}
@@ -53,14 +101,14 @@ jobs:
       env:
         MPICH_CXX: ${{matrix.compiler.CXX}}
         MPICH_CC: ${{matrix.compiler.CC}}
-      run: cmake --build ${{github.workspace}}/build --config ${{matrix.build_type}} -j --target install
+      run: cmake --build ${{github.workspace}}/build --target install
 
     - name: Test
       env:
         MPICH_CXX: ${{matrix.compiler.CXX}}
         MPICH_CC: ${{matrix.compiler.CC}}
       working-directory: ${{github.workspace}}/build
-      run: ctest --output-on-failure -C ${{matrix.build_type}}
+      run: ctest --output-on-failure
 
     - name: Build User Project
       # only need to test with a single build config if the installed cmake config files work
@@ -68,8 +116,11 @@ jobs:
       env:
         MPICH_CXX: ${{matrix.compiler.CXX}}
         MPICH_CC: ${{matrix.compiler.CC}}
-      run: |
-        cmake -S ${{github.workspace}}/doc -B ${{github.workspace}}/buildExample -DCMAKE_CXX_COMPILER=mpicxx -DSCOREC_PREFIX=${{github.workspace}}/build/install
+      run: >
+        cmake
+        -S ${{github.workspace}}/doc -B ${{github.workspace}}/buildExample
+        -DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx
+        -DSCOREC_PREFIX=${{github.workspace}}/build/install ;
         cmake --build ${{github.workspace}}/buildExample
 
     - name: Build MPI-NoMPI Example
@@ -81,10 +132,17 @@ jobs:
         MPICH_CXX: ${{matrix.compiler.CXX}}
         MPICH_CC: ${{matrix.compiler.CC}}
       run: >
-        cmake -S ${{github.workspace}}/example/mpi-nompi
+        cmake
+        -S ${{github.workspace}}/example/mpi-nompi
         -B ${{github.workspace}}/example/mpi-nompi/build
-        -DCMAKE_CXX_COMPILER=mpicxx
+        -DCMAKE_C_COMPILER=mpicxx -DCMAKE_CXX_COMPILER=mpicxx
         -DSCOREC_PREFIX=${{github.workspace}}/build/install ;
         cmake --build ${{github.workspace}}/example/mpi-nompi/build ;
         ctest --test-dir ${{github.workspace}}/example/mpi-nompi/build
         --output-on-failure
+
+    - name: CCache statistics and recompression
+      run: |
+        ccache -sv
+        ccache -X 5
+
diff --git a/.github/workflows/python-api-test.yml b/.github/workflows/python-api-test.yml
index 2d2d645b0..423f3f458 100644
--- a/.github/workflows/python-api-test.yml
+++ b/.github/workflows/python-api-test.yml
@@ -13,21 +13,57 @@ jobs:
     env:
       PYTHONPATH: ${{ github.workspace }}/build/python_wrappers
       LD_LIBRARY_PATH: ${{ github.workspace }}/libs/install/lib:${LD_LIBRARY_PATH}
+      CCACHE_DIR: ${{github.workspace}}/.ccache
+      CCACHE_BASEDIR: ${{github.workspace}}
+      CCACHE_COMPRESS: true
+      CCACHE_MAXSIZE: 100M
+      CMAKE_C_COMPILER_LAUNCHER: ccache
+      CMAKE_CXX_COMPILER_LAUNCHER: ccache
 
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
 
+      - name: setup cache timestamp
+        id: setup-cache
+        run: |
+          echo timestamp=$(date -u '+%Y-%m-%dT%T') >> "$GITHUB_OUTPUT"
+
+      - name: Cache pip
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/pip
+          key: "pyapi-pip-${{steps.setup-cache.outputs.timestamp}}"
+          restore-keys: pyapi-pip-
+
       - name: Install dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y cmake mpich build-essential libbz2-dev
+          sudo apt-get install -y mpich libbz2-dev ccache
+          mkdir -p /opt/ccache/libexec
+          ln -s $(which ccache) /opt/ccache/libexec/gcc
+          ln -s $(which ccache) /opt/ccache/libexec/g++
+          ln -s $(which ccache) /opt/ccache/libexec/cc
+          ln -s $(which ccache) /opt/ccache/libexec/c++
           pip3 install mpi4py
-      
+
+      - name: ccache
+        uses: actions/cache@v4
+        with:
+          path: ${{github.workspace}}/.ccache
+          key: "pyapi-ccache-${{steps.setup-cache.outputs.timestamp}}"
+          restore-keys: "pyapi-ccache-"
+
+      - name: Clear ccache statistics
+        run: |
+          ccache -p # Print ccache config
+          ccache -z
+
       - name: Build SWIG
         run: |
           git clone https://github.com/swig/swig.git
           cd swig
+          export PATH=/opt/ccache/libexec:$PATH
           ./autogen.sh
           ./configure --prefix=${{ github.workspace }}/libs/install
           make
@@ -56,10 +92,9 @@ jobs:
 
       - name: Build Zoltan from Trilinos (minimal)
         run: |
-          git clone https://github.com/trilinos/Trilinos.git
-          mkdir build-zoltan
-          cd build-zoltan
-          cmake ../Trilinos \
+          git clone --depth 1 https://github.com/trilinos/Trilinos.git
+          cmake -S Trilinos -B build-zoltan \
+            -GNinja \
             -DCMAKE_INSTALL_PREFIX=${{ github.workspace }}/libs/install \
             -DTPL_ENABLE_MPI:BOOL=ON \
             -DCMAKE_C_FLAGS="-O3 -fPIC" \
@@ -71,12 +106,12 @@ jobs:
             -DZoltan_ENABLE_ParMETIS:BOOL=ON \
             -DParMETIS_INCLUDE_DIRS=${{ github.workspace }}/libs/install \
             -DParMETIS_LIBRARY_DIRS=${{ github.workspace }}/libs/install
-          make
-          make install
+          cmake --build build-zoltan -t install
 
       - name: Configure PUMI
         run: |
           cmake -S . -B build \
+            -GNinja \
             -DCMAKE_INSTALL_PREFIX=${{ github.workspace }}/build/install \
             -DCMAKE_C_COMPILER=mpicc \
             -DCMAKE_CXX_COMPILER=mpicxx \
@@ -93,11 +128,16 @@ jobs:
             -DPARMETIS_PREFIX=${{ github.workspace }}/libs/install \
             -DENABLE_SIMMETRIX=OFF
 
-      - name: Build and install
+      - name: Build and install PUMI
         run: |
-          cmake --build build -j 4 --target install
+          cmake --build build --target install
 
       - name: Run Python test
         working-directory: ${{github.workspace}}/python_wrappers
         run: |
           python3 test_pyCore.py -g input/cube.dmg -m input/cube.smb
+
+      - name: Ccache statistics and recompression
+        run: |
+          ccache -sv
+          ccache -X 5