diff --git a/.github/workflows/build_all.yml b/.github/workflows/build_all.yml
index 41fe9d2302..41f2573a24 100644
--- a/.github/workflows/build_all.yml
+++ b/.github/workflows/build_all.yml
@@ -194,7 +194,7 @@ jobs:
         restore-keys: flatpak-builder-${{ matrix.variant.arch }}-
     - name: Disable debug info for faster CI builds
       run: |
-        sed -i '/^build-options:/a\  no-debuginfo: true\n  strip: true' \
+        sed -i '/^build-options:/a\  no-debuginfo: true\n  strip: true\n  cflags: "-g0"\n  cxxflags: "-g0"' \
           scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml
       shell: bash
     - name: Inject git commit hash into Flatpak manifest
@@ -202,6 +202,14 @@ jobs:
         sed -i "/name: OrcaSlicer/{n;s|buildsystem: simple|buildsystem: simple\n    build-options:\n      env:\n        git_commit_hash: \"$git_commit_hash\"|}" \
           scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml
       shell: bash
+    - name: Restore manifest mtime for deterministic cache keys
+      run: |
+        # sed changes mtime, which flatpak-builder uses for SOURCE_DATE_EPOCH
+        # and type:dir module cache keys. Restore to git commit time so cache
+        # keys are stable across builds of the same source.
+        touch -d @$(git log -1 --format='%ct' -- scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml) \
+          scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml
+      shell: bash
     - uses: flatpak/flatpak-github-actions/flatpak-builder@master
       with:
         bundle: OrcaSlicer-Linux-flatpak_${{ env.ver }}_${{ matrix.variant.arch }}.flatpak
diff --git a/build_flatpak.sh b/build_flatpak.sh
index 225cf25e66..af78376a49 100755
--- a/build_flatpak.sh
+++ b/build_flatpak.sh
@@ -20,8 +20,8 @@ CLEANUP=false
 INSTALL_RUNTIME=false
 JOBS=$(nproc)
 FORCE_CLEAN=false
-ENABLE_CCACHE=false
-DISABLE_ROFILES_FUSE=false
+ENABLE_CCACHE=true
+DISABLE_ROFILES_FUSE=true
 NO_DEBUGINFO=true
 CACHE_DIR=".flatpak-builder"
 
@@ -37,19 +37,19 @@ show_help() {
     echo "  -j, --jobs JOBS        Number of parallel build jobs for flatpak-builder and modules [default: $JOBS]"
     echo "  -c, --cleanup          Clean build directory before building"
     echo "  -f, --force-clean      Force clean build (disables caching)"
-    echo "  --ccache               Enable ccache for faster rebuilds (requires ccache in SDK)"
-    echo "  --disable-rofiles-fuse Disable rofiles-fuse (workaround for FUSE issues)"
+    echo "  --no-ccache            Disable ccache (enabled by default)"
+    echo "  --enable-rofiles-fuse  Enable rofiles-fuse (disabled by default as workaround for FUSE issues)"
     echo "  --with-debuginfo       Include debug info (slower builds, needed for Flathub)"
     echo "  --cache-dir DIR        Flatpak builder cache directory [default: $CACHE_DIR]"
     echo "  -i, --install-runtime  Install required Flatpak runtime and SDK"
     echo "  -h, --help             Show this help message"
     echo ""
     echo "Examples:"
-    echo "  $0                     # Build for current architecture with caching enabled"
+    echo "  $0                     # Build with defaults (ccache enabled, rofiles-fuse disabled)"
     echo "  $0 -f                  # Force clean build (no caching)"
-    echo "  $0 --ccache -j 8       # Use ccache and 8 parallel jobs for faster builds"
+    echo "  $0 --no-ccache -j 8    # Disable ccache and use 8 parallel jobs"
     echo "  $0 -a x86_64 -c       # Build for x86_64 and cleanup first"
-    echo "  $0 -i -j 16 --ccache  # Install runtime, build with 16 jobs and ccache"
+    echo "  $0 -i -j 16           # Install runtime and build with 16 jobs"
 }
 
 # Parse command line arguments
@@ -75,12 +75,12 @@ while [[ $# -gt 0 ]]; do
             FORCE_CLEAN=true
             shift
             ;;
-        --ccache)
-            ENABLE_CCACHE=true
+        --no-ccache)
+            ENABLE_CCACHE=false
             shift
             ;;
-        --disable-rofiles-fuse)
-            DISABLE_ROFILES_FUSE=true
+        --enable-rofiles-fuse)
+            DISABLE_ROFILES_FUSE=false
             shift
             ;;
         --with-debuginfo)
@@ -249,9 +249,13 @@ if [[ "$CLEANUP" == true ]]; then
     echo -e "${BLUE}Note: Host build directories (deps/build, build) are preserved${NC}"
 fi
 
-# Create build directory
+# Create build directory and set up log file
 mkdir -p "$BUILD_DIR"
 rm -rf "$BUILD_DIR/build-dir"
+LOG_FILE="$BUILD_DIR/build_flatpak_$(date +'%Y%m%d_%H%M%S').log"
+exec > >(tee -a "$LOG_FILE") 2>&1
+echo -e "${BLUE}Logging to: ${GREEN}$LOG_FILE${NC}"
+echo ""
 
 # Check if flatpak manifest exists
 if [[ ! -f "./scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml" ]]; then
@@ -303,6 +307,13 @@ else
 fi
 
 # Add ccache if enabled
+# NOTE: flatpak-builder's --ccache only creates symlinks for gcc/g++, not
+# clang/clang++. The actual ccache integration is done via
+# CMAKE_C_COMPILER_LAUNCHER=ccache in the manifest's build-commands.
+# --ccache is still needed because it:
+#   1. Bind-mounts the ccache directory into the sandbox at /run/ccache
+#   2. Sets CCACHE_DIR=/run/ccache for persistent caching
+#   3. Makes /usr/bin/ccache available in the build environment
 if [[ "$ENABLE_CCACHE" == true ]]; then
     BUILDER_ARGS+=(--ccache)
     echo -e "${GREEN}Using ccache for compiler caching${NC}"
@@ -318,9 +329,12 @@ fi
 MANIFEST="scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml"
 if [[ "$NO_DEBUGINFO" == true ]]; then
     MANIFEST="scripts/flatpak/io.github.orcaslicer.OrcaSlicer.no-debug.yml"
-    sed '/^build-options:/a\  no-debuginfo: true\n  strip: true' \
+    sed '/^build-options:/a\  no-debuginfo: true\n  strip: true\n  cflags: "-g0"\n  cxxflags: "-g0"' \
         scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml > "$MANIFEST"
-    echo -e "${YELLOW}Debug info disabled (using temp manifest)${NC}"
+    # Preserve original manifest's mtime so flatpak-builder computes a
+    # deterministic SOURCE_DATE_EPOCH and module cache keys stay stable.
+    touch -r scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml "$MANIFEST"
+    echo -e "${YELLOW}Debug info disabled (using temp manifest with -g0)${NC}"
 fi
 
 if ! flatpak-builder \
@@ -328,7 +342,7 @@ if ! flatpak-builder \
     "$BUILD_DIR/build-dir" \
     "$MANIFEST"; then
     echo -e "${RED}Error: flatpak-builder failed${NC}"
-    echo -e "${YELLOW}Check the build log above for details${NC}"
+    echo -e "${YELLOW}Check the build log for details: $LOG_FILE${NC}"
     rm -f "scripts/flatpak/io.github.orcaslicer.OrcaSlicer.no-debug.yml"
     exit 1
 fi
@@ -336,6 +350,15 @@ fi
 # Clean up temp manifest
 rm -f "scripts/flatpak/io.github.orcaslicer.OrcaSlicer.no-debug.yml"
 
+# Show ccache statistics if ccache was enabled
+if [[ "$ENABLE_CCACHE" == true ]]; then
+    echo -e "${BLUE}=== ccache statistics ===${NC}"
+    CCACHE_DIR="$CACHE_DIR/ccache" ccache -sv 2>/dev/null || \
+    CCACHE_DIR="$CACHE_DIR/ccache" ccache -s 2>/dev/null || \
+    echo -e "${YELLOW}Could not retrieve ccache stats${NC}"
+    echo ""
+fi
+
 # Create bundle
 echo -e "${YELLOW}Creating Flatpak bundle...${NC}"
 if ! flatpak build-bundle \
@@ -352,6 +375,7 @@ echo ""
 echo -e "${GREEN}✓ Flatpak build completed successfully!${NC}"
 echo -e "Bundle created: ${GREEN}$BUNDLE_NAME${NC}"
 echo -e "Size: ${GREEN}$(du -h "$BUNDLE_NAME" | cut -f1)${NC}"
+echo -e "Build log: ${GREEN}$LOG_FILE${NC}"
 if [[ "$FORCE_CLEAN" != true ]]; then
     echo -e "Build cache: ${GREEN}$CACHE_DIR${NC} (preserved for faster future builds)"
 fi
diff --git a/deps/CMakeLists.txt b/deps/CMakeLists.txt
index 1826c029d0..c8933b5304 100644
--- a/deps/CMakeLists.txt
+++ b/deps/CMakeLists.txt
@@ -188,6 +188,8 @@ if (NOT IS_CROSS_COMPILE OR NOT APPLE)
             -DCMAKE_DEBUG_POSTFIX:STRING=d
             -DCMAKE_C_COMPILER:STRING=${CMAKE_C_COMPILER}
             -DCMAKE_CXX_COMPILER:STRING=${CMAKE_CXX_COMPILER}
+            -DCMAKE_C_COMPILER_LAUNCHER:STRING=${CMAKE_C_COMPILER_LAUNCHER}
+            -DCMAKE_CXX_COMPILER_LAUNCHER:STRING=${CMAKE_CXX_COMPILER_LAUNCHER}
             -DCMAKE_TOOLCHAIN_FILE:STRING=${CMAKE_TOOLCHAIN_FILE}
             -DCMAKE_EXE_LINKER_FLAGS:STRING=${CMAKE_EXE_LINKER_FLAGS}
             -DCMAKE_SHARED_LINKER_FLAGS:STRING=${CMAKE_SHARED_LINKER_FLAGS}
@@ -232,6 +234,8 @@ else()
             -DCMAKE_POLICY_VERSION_MINIMUM=3.5
             -DCMAKE_INSTALL_PREFIX:STRING=${DESTDIR}
             -DCMAKE_PREFIX_PATH:STRING=${DESTDIR}
+            -DCMAKE_C_COMPILER_LAUNCHER:STRING=${CMAKE_C_COMPILER_LAUNCHER}
+            -DCMAKE_CXX_COMPILER_LAUNCHER:STRING=${CMAKE_CXX_COMPILER_LAUNCHER}
             -DBUILD_SHARED_LIBS:BOOL=OFF
             ${_cmake_osx_arch}
             "${_configs_line}"
diff --git a/scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml b/scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml
index b161f99477..6f90839059 100644
--- a/scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml
+++ b/scripts/flatpak/io.github.orcaslicer.OrcaSlicer.yml
@@ -14,6 +14,9 @@ build-options:
     CC: clang
     CXX: clang++
     LDFLAGS: "-fuse-ld=lld"
+    CCACHE_SLOPPINESS: "pch_defines,time_macros,include_file_mtime,include_file_ctime"
+    CCACHE_BASEDIR: "/run/build"
+    CCACHE_NOHASHDIR: "1"
 finish-args:
   - --share=ipc
   - --socket=x11
@@ -130,16 +133,26 @@ modules:
         BUILD_DIR: deps/build_flatpak
     build-commands:
       - |
+        CCACHE_LAUNCHER=""
+        if command -v ccache >/dev/null 2>&1; then
+          CCACHE_LAUNCHER="-DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache"
+        fi
         cmake -S deps -B $BUILD_DIR \
           -DFLATPAK=ON \
           -DDEP_DOWNLOAD_DIR=/run/build/orca_deps/external-packages \
           -DCMAKE_PREFIX_PATH=/app \
           -DDESTDIR=/app \
           -DCMAKE_INSTALL_PREFIX=/app \
+          $CCACHE_LAUNCHER \
           -DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld" \
           -DCMAKE_SHARED_LINKER_FLAGS="-fuse-ld=lld" \
           -DCMAKE_MODULE_LINKER_FLAGS="-fuse-ld=lld"
       - cmake --build $BUILD_DIR --parallel
+      - |
+        if command -v ccache >/dev/null 2>&1; then
+          echo "=== ccache statistics (after orca_deps) ==="
+          ccache -sv || ccache -s || true
+        fi
       - rm -rf /run/build/orca_deps/external-packages
 
     cleanup:
@@ -306,17 +319,28 @@ modules:
     buildsystem: simple
     build-commands:
       - |
+        CCACHE_LAUNCHER=""
+        if command -v ccache >/dev/null 2>&1; then
+          CCACHE_LAUNCHER="-DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache"
+        fi
         cmake . -B build_flatpak \
           -DFLATPAK=ON \
           -DCMAKE_BUILD_TYPE=Release \
           -DCMAKE_PREFIX_PATH=/app \
           -DCMAKE_INSTALL_PREFIX=/app \
+          $CCACHE_LAUNCHER \
+          -DSLIC3R_PCH=OFF \
           -DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld" \
           -DCMAKE_SHARED_LINKER_FLAGS="-fuse-ld=lld" \
           -DCMAKE_MODULE_LINKER_FLAGS="-fuse-ld=lld"
       - cmake --build build_flatpak --target OrcaSlicer -j$FLATPAK_BUILDER_N_JOBS
       - ./scripts/run_gettext.sh
       - cmake --build build_flatpak --target install -j$FLATPAK_BUILDER_N_JOBS
+      - |
+        if command -v ccache >/dev/null 2>&1; then
+          echo "=== ccache statistics (after OrcaSlicer) ==="
+          ccache -sv || ccache -s || true
+        fi
 
     cleanup:
       - /include