diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b3712909..357942ea 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -292,16 +292,19 @@ jobs:
             build_dist: alpine
             build_type: clang-relsize-lto-ninja-static
             cross_arch: riscv64
+            skip_slow_tests: true
 
           - build_arch: amd64
             build_dist: alpine
             build_type: clang-release-ninja-static
             cross_arch: riscv64
+            skip_slow_tests: true
 
           - build_arch: amd64
             build_dist: alpine
             build_type: gcc-release-ninja-static
             cross_arch: riscv64
+            skip_slow_tests: true
 
           - build_arch: amd64
             build_dist: alpine
@@ -312,16 +315,19 @@ jobs:
             build_dist: alpine
             build_type: clang-relsize-lto-ninja-static
             cross_arch: i386
+            skip_slow_tests: true
 
           - build_arch: amd64
             build_dist: alpine
             build_type: clang-release-ninja-static
             cross_arch: i386
+            skip_slow_tests: true
 
           - build_arch: amd64
             build_dist: alpine
             build_type: gcc-release-ninja-static
             cross_arch: i386
+            skip_slow_tests: true
 
           - build_arch: amd64
             build_dist: alpine
@@ -332,11 +338,13 @@ jobs:
             build_dist: alpine
             build_type: clang-relsize-lto-ninja-static
             cross_arch: arm
+            skip_slow_tests: true
 
           - build_arch: amd64
             build_dist: alpine
             build_type: clang-release-ninja-static
             cross_arch: arm
+            skip_slow_tests: true
 
           ######### fails: static_assert(std::atomic<bool>::is_always_lock_free);
           # - build_arch: amd64
@@ -355,6 +363,7 @@ jobs:
       build_arch: ${{ matrix.build_arch }}
       build_dist: ${{ matrix.build_dist }}
       cross_arch: ${{ matrix.cross_arch }}
+      skip_slow_tests: ${{ matrix.skip_slow_tests || false }}
       build_from_tarball: true
       upload_coverage: ${{ matrix.build_type == 'clang-debug-coverage-ninja' }}
       upload_artifacts: ${{ endsWith(matrix.build_type, '-static') }}
diff --git a/.github/workflows/docker-run-build.yml b/.github/workflows/docker-run-build.yml
index 7b714259..dccc935c 100644
--- a/.github/workflows/docker-run-build.yml
+++ b/.github/workflows/docker-run-build.yml
@@ -29,6 +29,10 @@ on:
         required: false
         type: boolean
         default: false
+      skip_slow_tests:
+        required: false
+        type: boolean
+        default: false
 
 permissions:
   contents: read
@@ -72,6 +76,7 @@ jobs:
             --mount type=bind,source=${HOME}/github-local,target=/local \
             --mount type=bind,source=/mnt/opensource/artifacts/dwarfs,target=/artifacts \
             ${{ inputs.build_from_tarball && '--env BUILD_FROM_TARBALL=1' || '' }} \
+            ${{ inputs.skip_slow_tests && '--env DWARFS_SKIP_SLOW_TESTS=1' || '' }} \
             --env BUILD_TYPE=${{ inputs.build_type }} \
             --env BUILD_ARCH=${{ inputs.build_arch }} \
             --env CROSS_ARCH=${{ inputs.cross_arch }} \
diff --git a/.maintainer-scripts/workflow-tracing.py b/.maintainer-scripts/workflow-tracing.py
index b5ee249d..8758f29f 100644
--- a/.maintainer-scripts/workflow-tracing.py
+++ b/.maintainer-scripts/workflow-tracing.py
@@ -136,7 +136,7 @@ def main():
                             if args.ninja and step.get("name") == "Run Build":
                                 run_id = job.get("run_id", 0)
                                 # get arch, dist, config from "linux (arm64v8, alpine, clang-release-ninja-static) / docker-build"
-                                m = re.match(r"linux \(([^,]+), ([^,]+), ([^,]+)(, ([^,]+))?\)", name)
+                                m = re.match(r"linux \(([^,]+), ([^,]+), ([^,]+)(, ([^,]+))?(, true)?\)", name)
                                 if m:
                                     cross = m.group(5) if m.group(5) else ""
                                     build_log_path = f"{args.log_base}/{run_id}/build-{m.group(1)},{cross},{m.group(2)},{m.group(3)}.log"
diff --git a/test/block_merger_test.cpp b/test/block_merger_test.cpp
index bfa4cbce..beb74f32 100644
--- a/test/block_merger_test.cpp
+++ b/test/block_merger_test.cpp
@@ -476,6 +476,8 @@ block_merger_test(size_t const max_runs) {
 } // namespace
 
 TEST(block_merger, random) {
+  DWARFS_SLOW_TEST();
+
   using merger_type = internal::multi_queue_block_merger<size_t, block>;
 
   auto max_runs = skip_slow_tests() ? max_runs_regular_quick : max_runs_regular;
@@ -487,6 +489,8 @@ TEST(block_merger, random) {
 }
 
 TEST(block_merger, random_sized) {
+  DWARFS_SLOW_TEST();
+
   using merger_type =
       internal::multi_queue_block_merger<size_t, sized_block,
                                          sized_block_merger_policy>;
@@ -500,6 +504,8 @@ TEST(block_merger, random_sized) {
 }
 
 TEST(block_merger, random_sized_partial) {
+  DWARFS_SLOW_TEST();
+
   using merger_type =
       internal::multi_queue_block_merger<size_t, sized_block,
                                          sized_block_merger_policy>;
diff --git a/test/tool_main_test.cpp b/test/tool_main_test.cpp
index e1f7ff5d..8e5c3289 100644
--- a/test/tool_main_test.cpp
+++ b/test/tool_main_test.cpp
@@ -2990,6 +2990,8 @@ TEST(mkdwarfs_test, map_file_error) {
 class map_file_error_test : public testing::TestWithParam<char const*> {};
 
 TEST_P(map_file_error_test, delayed) {
+  DWARFS_SLOW_TEST();
+
 #if defined(__linux__) && defined(__i386__)
   GTEST_SKIP() << "this test is flaky on i386 Linux (SIGPIPE)";
 #endif