diff --git a/ci/checkformat.gitlab-ci.yml b/ci/checkformat.gitlab-ci.yml
index ea1ec5663..a0becc7d2 100644
--- a/ci/checkformat.gitlab-ci.yml
+++ b/ci/checkformat.gitlab-ci.yml
@@ -44,3 +44,9 @@ checkformat:clangtidy:
         -DEIGEN_BUILD_TESTING=ON
     - chmod +x ci/scripts/run-clang-tidy.sh
     - ci/scripts/run-clang-tidy.sh ${CI_MERGE_REQUEST_DIFF_BASE_SHA} .tidy-build
+  cache:
+    key: clang-tidy-config
+    paths:
+      - .tidy-build/compile_commands.json
+      - .tidy-build/CMakeCache.txt
+      - .tidy-build/CMakeFiles/
diff --git a/ci/common.gitlab-ci.yml b/ci/common.gitlab-ci.yml
index dff86e845..df0367cbd 100644
--- a/ci/common.gitlab-ci.yml
+++ b/ci/common.gitlab-ci.yml
@@ -21,7 +21,11 @@
     name: "$CI_JOB_NAME_SLUG-$CI_COMMIT_REF_SLUG"
     paths:
       - ${EIGEN_CI_BUILDDIR}/
-    expire_in: 5 days
+    exclude:
+      - ${EIGEN_CI_BUILDDIR}/**/*.o
+      - ${EIGEN_CI_BUILDDIR}/**/.ninja_log
+      - ${EIGEN_CI_BUILDDIR}/**/.ninja_deps
+    expire_in: 2 days
 
 # Base configuration for Windows builds and tests.
 .common:windows:
@@ -37,4 +41,8 @@
     name: "$CI_JOB_NAME_SLUG-$CI_COMMIT_REF_NAME"
     paths:
       - ${EIGEN_CI_BUILDDIR}/
-    expire_in: 5 days
+    exclude:
+      - ${EIGEN_CI_BUILDDIR}/**/*.obj
+      - ${EIGEN_CI_BUILDDIR}/**/.ninja_log
+      - ${EIGEN_CI_BUILDDIR}/**/.ninja_deps
+    expire_in: 2 days
diff --git a/ci/scripts/test.linux.script.sh b/ci/scripts/test.linux.script.sh
index e0d2c21e4..dcf9cb646 100755
--- a/ci/scripts/test.linux.script.sh
+++ b/ci/scripts/test.linux.script.sh
@@ -16,6 +16,7 @@ fi
 set +x
 
 EIGEN_CI_CTEST_PARALLEL=${EIGEN_CI_CTEST_PARALLEL:-${NPROC}}
+EIGEN_CI_CTEST_REPEAT=${EIGEN_CI_CTEST_REPEAT:-3}
 ctest_cmd="ctest ${EIGEN_CI_CTEST_ARGS} --parallel ${EIGEN_CI_CTEST_PARALLEL} --output-on-failure --no-compress-output --build-noclean ${target}"
 
 echo "Running initial tests..."
diff --git a/ci/test.linux.gitlab-ci.yml b/ci/test.linux.gitlab-ci.yml
index 16ea5cb34..b093cc2b3 100644
--- a/ci/test.linux.gitlab-ci.yml
+++ b/ci/test.linux.gitlab-ci.yml
@@ -307,6 +307,7 @@ test:linux:cuda-13.1:nvhpc-26.1:
     EIGEN_CI_TARGET_ARCH: arm
     EIGEN_CI_CROSS_TARGET_TRIPLE: arm-linux-gnueabihf
     EIGEN_CI_CTEST_ARGS: --timeout 2000
+    EIGEN_CI_CTEST_PARALLEL: "4"
 
 .test:linux:arm:gcc-10:default:
   extends: .test:linux:arm
@@ -391,6 +392,7 @@ test:linux:aarch64:clang-12:default:unsupported:
     EIGEN_CI_TARGET_ARCH: ppc64le
     EIGEN_CI_CROSS_TARGET_TRIPLE: powerpc64le-linux-gnu
     EIGEN_CI_CTEST_ARGS: --timeout 2000
+    EIGEN_CI_CTEST_PARALLEL: "4"
 
 .test:linux:ppc64le:gcc-14:default:
   extends: .test:linux:ppc64le
@@ -434,6 +436,7 @@ test:linux:ppc64le:clang-16:default:unsupported:
     EIGEN_CI_CROSS_TARGET_TRIPLE: loongarch64-linux-gnu
     EIGEN_CI_CROSS_INSTALL: g++-14-loongarch64-linux-gnu qemu-user-static
     EIGEN_CI_CTEST_ARGS: --timeout 2000
+    EIGEN_CI_CTEST_PARALLEL: "4"
 
 # GCC-14 (Ubuntu 24)
 .test:linux:loongarch64:gcc-14:default: