diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 659e7256..4b11cbb6 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -7,6 +7,7 @@ on:
     - 'docs/**'
   pull_request:
     branches: [ "main" ]
+    types: [opened, reopened, synchronize, labeled]
     paths-ignore:
     - 'docs/**'
   schedule:
@@ -36,12 +37,27 @@ jobs:
 
       - name: List installed libraries
         run: |
-          pixi install --environment ${{ matrix.environment }}
           pixi list --environment ${{ matrix.environment }}
 
-      - name: Running Tests
+      - name: Determine test type
+        id: test-type
         run: |
-          pixi run -e ${{ matrix.environment }} run-tests-xml-cov
+          if [[ "${{ github.event_name }}" == "pull_request" ]] && \
+             [[ "${{ contains(github.event.pull_request.labels.*.name, 'test-slow') }}" == "true" ]]; then
+            echo "run-slow=true" >> $GITHUB_OUTPUT
+            echo "Running slow tests due to 'test-slow' label"
+          else
+            echo "run-slow=false" >> $GITHUB_OUTPUT
+            echo "Running standard tests (skipping slow tests)"
+          fi
+
+      - name: Run Tests
+        run: |
+          if [[ "${{ steps.test-type.outputs.run-slow }}" == "true" ]]; then
+            pixi run -e ${{ matrix.environment }} run-tests-including-slow
+          else
+            pixi run -e ${{ matrix.environment }} run-tests-xml-cov
+          fi
 
       - name: Upload code coverage to Codecov
         uses: codecov/codecov-action@v3.1.4
diff --git a/.github/workflows/minimum-versions.yml b/.github/workflows/minimum-versions.yml
index 514b6ae1..11e30c1e 100644
--- a/.github/workflows/minimum-versions.yml
+++ b/.github/workflows/minimum-versions.yml
@@ -39,12 +39,26 @@ jobs:
 
       - name: List installed libraries
         run: |
-          pixi install --environment minimum-versions
           pixi list --environment minimum-versions
-      - name: Running Tests
+      - name: Determine test type
+        id: test-type
         run: |
-          pixi run -e minimum-versions run-tests-xml-cov
+          if [[ "${{ github.event_name }}" == "pull_request" ]] && \
+             [[ "${{ contains(github.event.pull_request.labels.*.name, 'test-slow') }}" == "true" ]]; then
+            echo "run-slow=true" >> $GITHUB_OUTPUT
+            echo "Running slow tests due to 'test-slow' label"
+          else
+            echo "run-slow=false" >> $GITHUB_OUTPUT
+            echo "Running standard tests (skipping slow tests)"
+          fi
 
+      - name: Run Tests
+        run: |
+          if [[ "${{ steps.test-type.outputs.run-slow }}" == "true" ]]; then
+            pixi run -e minimum-versions run-tests-including-slow
+          else
+            pixi run -e minimum-versions run-tests-xml-cov
+          fi
       - name: Upload code coverage to Codecov
         uses: codecov/codecov-action@v3.1.4
         with:
diff --git a/.github/workflows/upstream.yml b/.github/workflows/upstream.yml
index fdce3a56..5fac16e6 100644
--- a/.github/workflows/upstream.yml
+++ b/.github/workflows/upstream.yml
@@ -40,12 +40,27 @@ jobs:
 
       - name: List installed libraries
         run: |
-          pixi install --environment upstream
           pixi list --environment upstream
 
-      - name: Running Tests
+      - name: Determine test type
+        id: test-type
         run: |
-          pixi run -e upstream run-tests-xml-cov
+          if [[ "${{ github.event_name }}" == "pull_request" ]] && \
+             [[ "${{ contains(github.event.pull_request.labels.*.name, 'test-slow') }}" == "true" ]]; then
+            echo "run-slow=true" >> $GITHUB_OUTPUT
+            echo "Running slow tests due to 'test-slow' label"
+          else
+            echo "run-slow=false" >> $GITHUB_OUTPUT
+            echo "Running standard tests (skipping slow tests)"
+          fi
+
+      - name: Run Tests
+        run: |
+          if [[ "${{ steps.test-type.outputs.run-slow }}" == "true" ]]; then
+            pixi run -e upstream run-tests-including-slow
+          else
+            pixi run -e upstream run-tests-xml-cov
+          fi
 
       - name: Upload code coverage to Codecov
         uses: codecov/codecov-action@v3.1.4
diff --git a/pyproject.toml b/pyproject.toml
index aeafacb7..8df38342 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -177,7 +177,7 @@ run-mypy = { cmd = "mypy virtualizarr" }
 # Using '--dist loadscope' (rather than default of '--dist load' when '-n auto'
 # is used), reduces test hangs that appear to be macOS-related.
 run-tests = { cmd = "pytest -n auto --dist loadscope --run-network-tests --verbose --durations=10" }
-run-tests-including-slow = { cmd = "pytest -n auto --dist loadscope --run-network-tests --run-slow-tests --verbose --durations=10" }
+run-tests-including-slow = { cmd = "pytest -n auto --dist loadscope --run-network-tests --run-slow-tests --verbose --durations=10 --cov=virtualizarr --cov-report=xml" }
 run-tests-no-network = { cmd = "pytest -n auto --verbose" }
 run-tests-cov = { cmd = "pytest -n auto --run-network-tests --verbose --cov=virtualizarr --cov=term-missing" }
 run-tests-xml-cov = { cmd = "pytest -n auto --run-network-tests --verbose --cov=virtualizarr --cov-report=xml" }
@@ -206,6 +206,7 @@ readthedocs = { cmd = "rm -rf $READTHEDOCS_OUTPUT/html && cp -r site $READTHEDOC
 [tool.pixi.feature.minio.tasks]
 run-tests = { cmd = "pytest virtualizarr/tests/test_manifests/test_store.py virtualizarr/tests/test_parsers/test_hdf/test_hdf_manifest_store.py --run-minio-tests --run-network-tests --verbose" }
 run-tests-xml-cov = { cmd = "pytest virtualizarr/tests/test_manifests/test_store.py virtualizarr/tests/test_parsers/test_hdf/test_hdf_manifest_store.py --run-minio-tests --run-network-tests --verbose --cov-report=xml" }
+run-tests-including-slow= { cmd = "pytest virtualizarr/tests/test_manifests/test_store.py virtualizarr/tests/test_parsers/test_hdf/test_hdf_manifest_store.py --run-minio-tests --run-network-tests --run-slow-tests --verbose --cov-report=xml" }
 
 [tool.setuptools_scm]
 fallback_version = "9999"