diff --git a/.github/actions/calculate-shard-matrix/action.yaml b/.github/actions/calculate-shard-matrix/action.yaml
new file mode 100644
index 000000000000..660e725ee84f
--- /dev/null
+++ b/.github/actions/calculate-shard-matrix/action.yaml
@@ -0,0 +1,22 @@
+name: "Calculate Shard Matrix"
+description: "Calculates the dynamic test shard matrix and shard total"
+outputs:
+  shard_matrix:
+    description: "JSON array of shard indices"
+    value: ${{ steps.set-matrix.outputs.shard_matrix }}
+  shard_total:
+    description: "Total number of shards"
+    value: ${{ steps.set-matrix.outputs.shard_total }}
+runs:
+  using: "composite"
+  steps:
+    - name: Calculate Matrix
+      id: set-matrix
+      shell: bash
+      env:
+        DRY_RUN_SHARDS: true
+        BUILD_TYPE: presubmit
+        TEST_TYPE: units
+        GIT_DIFF_ARG: "HEAD^1"
+      run: |
+        bash ci/run_conditional_tests.sh --strict
diff --git a/.github/actions/check-shard-status/action.yaml b/.github/actions/check-shard-status/action.yaml
new file mode 100644
index 000000000000..37f57a2992ae
--- /dev/null
+++ b/.github/actions/check-shard-status/action.yaml
@@ -0,0 +1,31 @@
+name: "Check Shard Status"
+description: "Checks if all unit test shards passed for a given Node version"
+inputs:
+  node-version:
+    required: true
+    description: "Node version to check"
+runs:
+  using: "composite"
+  steps:
+    - name: Check shard status
+      uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+      with:
+        script: |
+          const { data: { jobs } } = await github.rest.actions.listJobsForWorkflowRun({
+            owner: context.repo.owner,
+            repo: context.repo.repo,
+            run_id: context.runId,
+          });
+          const nodeVersion = '${{ inputs.node-version }}';
+          const shardJobs = jobs.filter(j => j.name.includes(`units (Node ${nodeVersion},`));
+          if (shardJobs.length === 0) {
+            core.setFailed(`No shard jobs found for Node ${nodeVersion}`);
+            return;
+          }
+          const failed = shardJobs.filter(j => j.conclusion === 'failure' || j.conclusion === 'cancelled');
+          if (failed.length > 0) {
+            const failedLinks = failed.map(j => `- ${j.name}: ${j.html_url}`).join('\n');
+            core.setFailed(`${failed.length} shards failed for Node ${nodeVersion}:\n${failedLinks}`);
+          } else {
+            core.info(`All shards passed for Node ${nodeVersion}`);
+          }
diff --git a/.github/actions/run-unit-tests/action.yaml b/.github/actions/run-unit-tests/action.yaml
new file mode 100644
index 000000000000..69bf22693bdc
--- /dev/null
+++ b/.github/actions/run-unit-tests/action.yaml
@@ -0,0 +1,33 @@
+name: "Run Unit Test Shard"
+description: "Sets up Node.js, pnpm, and runs a unit test shard"
+inputs:
+  node-version:
+    required: true
+    description: "Node.js version to test"
+  shard-total:
+    required: true
+    description: "Total number of shards"
+  shard-index:
+    required: true
+    description: "0-based shard index"
+runs:
+  using: "composite"
+  steps:
+    - name: Use Node.js ${{ inputs.node-version }}
+      uses: actions/setup-node@249970729cb0ef3589644e2896645e5dc5ba9c38 # v6.5.0
+      with:
+        node-version: ${{ inputs.node-version }}
+    - uses: pnpm/action-setup@b906affcce14559ad1aafd4ab0e942779e9f58b1 # v4
+      with:
+        version: ^10.0.0
+    - run: node --version
+      shell: bash
+    - name: Run unit tests
+      shell: bash
+      run: bash ci/run_conditional_tests.sh --strict
+      env:
+        BUILD_TYPE: presubmit
+        TEST_TYPE: units
+        SHARD_TOTAL: ${{ inputs.shard-total }}
+        SHARD_INDEX: ${{ inputs.shard-index }}
+        GIT_DIFF_ARG: HEAD^1
diff --git a/.github/workflows/presubmit.yaml b/.github/workflows/presubmit.yaml
index c5de30eba54e..902233f76caa 100644
--- a/.github/workflows/presubmit.yaml
+++ b/.github/workflows/presubmit.yaml
@@ -5,29 +5,37 @@ on:
   pull_request:
 name: presubmit
 jobs:
+  setup:
+    runs-on: ubuntu-latest
+    outputs:
+      shard-matrix: ${{ steps.set-matrix.outputs.shard_matrix }}
+      shard-total: ${{ steps.set-matrix.outputs.shard_total }}
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
+        with:
+          fetch-depth: 2
+          persist-credentials: false
+      - id: set-matrix
+        uses: ./.github/actions/calculate-shard-matrix
   units:
+    needs: setup
+    name: units (Node ${{ matrix.node-version }}, Shard ${{ matrix.shard-index }})
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         node-version: [22, 24, 26]
+        shard-index: ${{ fromJSON(needs.setup.outputs.shard-matrix) }}
     steps:
       - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
         with:
-          fetch-depth: 300
+          fetch-depth: 2
           persist-credentials: false
-      - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@249970729cb0ef3589644e2896645e5dc5ba9c38 # v6.5.0
+      - uses: ./.github/actions/run-unit-tests
         with:
           node-version: ${{ matrix.node-version }}
-      - uses: pnpm/action-setup@b906affcce14559ad1aafd4ab0e942779e9f58b1 # v4
-        with:
-          version: ^10.0.0
-      - run: node --version
-      - run: ci/run_conditional_tests.sh
-        name: Run unit tests
-        env:
-          BUILD_TYPE: presubmit
-          TEST_TYPE: units
+          shard-total: ${{ needs.setup.outputs.shard-total }}
+          shard-index: ${{ matrix.shard-index }}
   lint:
     runs-on: ubuntu-latest
     continue-on-error: true
@@ -42,6 +50,25 @@ jobs:
           node-version: 24
       - run: npm install
       - run: node ./bin/linter.mjs --strict
-        name: Run monorepo linter
         env:
           GIT_DIFF_ARG: "HEAD^1"
+
+  # Dummy jobs to satisfy branch protection requirements for each node version
+  units-status:
+    name: units (${{ matrix.node-version }})
+    needs: units
+    runs-on: ubuntu-latest
+    if: always()
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: [22, 24, 26]
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
+        with:
+          persist-credentials: false
+      - name: Check shard status
+        uses: ./.github/actions/check-shard-status
+        with:
+          node-version: ${{ matrix.node-version }}
+>>>>>>> 657c33a5f3 (feat(ci): run unit-tests in parallel to speed them up)
diff --git a/.github/workflows/windows-presubmit.yaml b/.github/workflows/windows-presubmit.yaml
index 31105cfa46de..afd68aee344a 100644
--- a/.github/workflows/windows-presubmit.yaml
+++ b/.github/workflows/windows-presubmit.yaml
@@ -5,27 +5,53 @@ on:
   pull_request:
 name: presubmit-windows
 jobs:
+  setup:
+    runs-on: ubuntu-latest
+    outputs:
+      shard-matrix: ${{ steps.set-matrix.outputs.shard_matrix }}
+      shard-total: ${{ steps.set-matrix.outputs.shard_total }}
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
+        with:
+          fetch-depth: 2
+          persist-credentials: false
+      - id: set-matrix
+        uses: ./.github/actions/calculate-shard-matrix
   units:
+    needs: setup
+    name: units (Node ${{ matrix.node-version }}, Shard ${{ matrix.shard-index }})
     runs-on: windows-latest
     strategy:
+      fail-fast: false
       matrix:
         node-version: [22, 24, 26]
+        shard-index: ${{ fromJSON(needs.setup.outputs.shard-matrix) }}
     steps:
       - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
         with:
-          fetch-depth: 300
+          fetch-depth: 2
           persist-credentials: false
-      - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@249970729cb0ef3589644e2896645e5dc5ba9c38 # v6.5.0
+      - uses: ./.github/actions/run-unit-tests
         with:
           node-version: ${{ matrix.node-version }}
-      - uses: pnpm/action-setup@b906affcce14559ad1aafd4ab0e942779e9f58b1 # v4
+          shard-total: ${{ needs.setup.outputs.shard-total }}
+          shard-index: ${{ matrix.shard-index }}
+
+  # Dummy jobs to satisfy branch protection requirements for each node version
+  units-status:
+    name: units (${{ matrix.node-version }})
+    needs: units
+    runs-on: ubuntu-latest
+    if: always()
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: [22, 24, 26]
+    steps:
+      - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803 # v6.1.0
         with:
-          version: ^10.0.0
-      - run: node --version
-      - run: bash ci/run_conditional_tests.sh
-        name: Run windows unit tests
-        shell: bash
-        env:
-          BUILD_TYPE: presubmit
-          TEST_TYPE: units
+          persist-credentials: false
+      - name: Check shard status
+        uses: ./.github/actions/check-shard-status
+        with:
+          node-version: ${{ matrix.node-version }}
diff --git a/ci/run_conditional_tests.sh b/ci/run_conditional_tests.sh
index cb6ae744a087..29f42bf888b2 100755
--- a/ci/run_conditional_tests.sh
+++ b/ci/run_conditional_tests.sh
@@ -36,25 +36,50 @@ if [[ "$(node -v)" == v22* ]]; then
   export NODE_OPTIONS="${NODE_OPTIONS} --no-experimental-require-module"
 fi
 
-if [ ${BUILD_TYPE} == "presubmit" ]; then
-    # For presubmit build, we want to know the difference from the
-    # common commit in origin/main.
-    GIT_DIFF_ARG="origin/main..."
+for arg in "$@"; do
+    case "${arg}" in
+        --strict)
+            STRICT=true
+            ;;
+    esac
+done
 
-    # Then fetch enough history for finding the common commit.
-    git fetch origin main --deepen=300
+if [[ "${STRICT}" == "true" || "${STRICT}" == "1" ]]; then
+    if [ -z "${GIT_DIFF_ARG}" ]; then
+        echo "Error: STRICT mode requires GIT_DIFF_ARG to be set." >&2
+        exit 1
+    fi
+    set +e
+    git diff --quiet ${GIT_DIFF_ARG}
+    diff_status=$?
+    set -e
+    if [[ ${diff_status} -ne 0 && ${diff_status} -ne 1 ]]; then
+        echo "Error: STRICT mode git diff ${GIT_DIFF_ARG} failed with exit code ${diff_status}." >&2
+        exit 1
+    fi
+else
+    if [ -z "${GIT_DIFF_ARG}" ]; then
+        if [ "${BUILD_TYPE}" == "presubmit" ]; then
+            # For presubmit build, we want to know the difference from the
+            # common commit in origin/main.
+            GIT_DIFF_ARG="origin/main..."
 
-elif [ ${BUILD_TYPE} == "continuous" ]; then
-    # For continuous build, we want to know the difference in the last
-    # commit. This assumes we use squash commit when merging PRs.
-    GIT_DIFF_ARG="HEAD~.."
+            # Then fetch enough history for finding the common commit.
+            git fetch origin main --deepen=300
 
-    # Then fetch one last commit for getting the diff.
-    git fetch origin main --deepen=1
+        elif [ "${BUILD_TYPE}" == "continuous" ]; then
+            # For continuous build, we want to know the difference in the last
+            # commit. This assumes we use squash commit when merging PRs.
+            GIT_DIFF_ARG="HEAD~.."
 
-else
-    # Run everything.
-    GIT_DIFF_ARG=""
+            # Then fetch one last commit for getting the diff.
+            git fetch origin main --deepen=1
+
+        else
+            # Run everything.
+            GIT_DIFF_ARG=""
+        fi
+    fi
 fi
 
 # Then detect changes in the test scripts.
@@ -66,11 +91,10 @@ set -e
 if [[ "${changed}" -eq 0 ]]; then
     echo "no change detected in ci"
 else
-    echo "skipping trigger of tests for now: tracking in #7540"
-    # echo "change detected in ci, we should test everything"
-    # echo "result of git diff ${GIT_DIFF_ARG} ci:"
-    # git diff ${GIT_DIFF_ARG} ci
-    # GIT_DIFF_ARG=""
+    echo "change detected in ci, we should test everything"
+    echo "result of git diff ${GIT_DIFF_ARG} ci:"
+    git diff ${GIT_DIFF_ARG} ci
+    GIT_DIFF_ARG=""
 fi
 
 # Now we have a fixed list, but we can change it to autodetect if
@@ -87,7 +111,7 @@ subdirs=(
 )
 
 RETVAL=0
-# These following APIs need an explicit credential file to run properly (or oAuth2, which we don't support in this repo). 
+# These following APIs need an explicit credential file to run properly (or oAuth2, which we don't support in this repo).
 # When we hit these packages, we will run the "samples with credentials" trigger, which contains the credentials as an env variable
 
 tests_with_credentials="core/packages/google-auth-library-nodejs/ packages/google-analytics-admin/ packages/google-area120-tables/ packages/google-analytics-data/ packages/google-iam-credentials/ packages/google-apps-meet/ packages/google-chat/ packages/google-streetview-publish/ packages/google-cloud-developerconnect/"
@@ -95,10 +119,13 @@ tests_with_credentials="core/packages/google-auth-library-nodejs/ packages/googl
 # Some packages are only used by our bots and automation. These packages do not need to run on Windows and
 # often employ platform specific code like file system interaction. Some packages may also fail
 # on Windows due to incompatible npm scripts.
-# 
+#
 # Until these packages can be updated to be OS agnostic, we will skip them on Windows.
 windows_exempt_tests="core/ core/packages/ core/dev-packages/ .github/scripts/fixtures/ .github/scripts/tests/ core/packages/gapic-node-processing/ core/packages/typeless-sample-bot/ handwritten/cloud-profiler/"
 
+# Gather all test directories into an array
+test_dirs=()
+
 for subdir in ${subdirs[@]}; do
     for d in `ls -d ${subdir}/*/`; do
         if [ -s "ignore.json" ] && jq -e ".ignored[] | select(. == \"$d\")" ignore.json > /dev/null 2>&1; then
@@ -121,7 +148,7 @@ for subdir in ${subdirs[@]}; do
         # System tests for packages are broken and blocking PRs.
         # See https://github.com/googleapis/google-cloud-node/issues/7976.
         #
-        # Per https://github.com/googleapis/google-cloud-node/issues/7921, 
+        # Per https://github.com/googleapis/google-cloud-node/issues/7921,
         # we are likely to permanently remove these tests in the near future.
         if [[ "${subdir}" == "packages" && "${TEST_TYPE}" == "system" ]]; then
             echo "Skipping ${TEST_TYPE} test for packages: ${d}"
@@ -131,7 +158,7 @@ for subdir in ${subdirs[@]}; do
         # Sample tests for packages are broken/flaky and blocking PRs.
         # See https://github.com/googleapis/google-cloud-node/issues/7976#issuecomment-4210458096.
         #
-        # Per https://github.com/googleapis/google-cloud-node/issues/7921, 
+        # Per https://github.com/googleapis/google-cloud-node/issues/7921,
         # we are likely to permanently remove these tests in the near future.
         if [[ "${subdir}" == "packages" && "${TEST_TYPE}" == "samples" ]]; then
             echo "Skipping ${TEST_TYPE} test for packages: ${d}"
@@ -209,21 +236,51 @@ for subdir in ${subdirs[@]}; do
             fi
         fi
         if [ "${should_test}" = true ]; then
-            echo "running test in ${d}"
-            pushd ${d}
-            # Temporarily allow failure.
-            set +e
-            ${test_script}
-            ret=$?
-            set -e
-            if [ ${ret} -ne 0 ]; then
-                RETVAL=${ret}
-                # Since there are so many APIs, we should exit early if there's an error
-                exit ${RETVAL}
-            fi
-            popd
+            test_dirs+=("${d}")
         fi
     done
 done
+# If DRY_RUN_SHARDS is set, output dynamic matrix values to GitHub Actions and exit
+if [[ "${DRY_RUN_SHARDS}" == "true" ]]; then
+    count=${#test_dirs[@]}
+    if [[ $count -gt 15 ]]; then
+        matrix="[0, 1, 2, 3, 4]"
+        total="5"
+    else
+        matrix="[0]"
+        total="1"
+    fi
+    if [[ -n "${GITHUB_OUTPUT}" ]]; then
+        echo "shard_matrix=${matrix}" >> "${GITHUB_OUTPUT}"
+        echo "shard_total=${total}" >> "${GITHUB_OUTPUT}"
+    else
+        echo "shard_matrix=${matrix}"
+        echo "shard_total=${total}"
+    fi
+    exit 0
+fi
+
+# If SHARD_TOTAL and SHARD_INDEX are provided, we will only run a subset of the tests.
+for i in "${!test_dirs[@]}"; do
+    d="${test_dirs[$i]}"
+
+    if [[ -n "${SHARD_TOTAL}" && -n "${SHARD_INDEX}" ]]; then
+        if (( SHARD_TOTAL > 0 && i % SHARD_TOTAL != SHARD_INDEX )); then
+            continue
+        fi
+    fi
+
+    echo "running test in ${d}"
+    pushd "${d}" >/dev/null
+    # Temporarily allow failure.
+    set +e
+    "${test_script}"
+    ret=$?
+    set -e
+    if [ ${ret} -ne 0 ]; then
+        exit ${ret}
+    fi
+    popd >/dev/null
+done
 
-exit ${RETVAL}
+exit 0
diff --git a/ci/run_single_test.sh b/ci/run_single_test.sh
index 662a1184f347..3dfd98ee7a2b 100755
--- a/ci/run_single_test.sh
+++ b/ci/run_single_test.sh
@@ -37,6 +37,8 @@ if [ ${BUILD_TYPE} != "presubmit" ]; then
     export MOCHA_REPORTER_OUTPUT=${PROJECT}_sponge_log.xml
     export MOCHA_REPORTER_SUITENAME=${PROJECT}
     export MOCHA_REPORTER=xunit
+else
+    export MOCHA_REPORTER=dot
 fi
 
 # Install dependencies
@@ -47,8 +49,8 @@ if command -v cygpath >/dev/null 2>&1; then
     PNPMFILE_PATH=$(cygpath -m "${PNPMFILE_PATH}")
 fi
 
-echo "pnpm install --ignore-scripts --engine-strict --prod --pnpmfile \"${PNPMFILE_PATH}\"; pnpm install --pnpmfile \"${PNPMFILE_PATH}\""
-pnpm install --ignore-scripts --engine-strict --prod --pnpmfile "${PNPMFILE_PATH}"; pnpm install --pnpmfile "${PNPMFILE_PATH}"
+echo "pnpm install --engine-strict --pnpmfile \"${PNPMFILE_PATH}\""
+pnpm install --engine-strict --pnpmfile "${PNPMFILE_PATH}"
 
 
 retval=0
diff --git a/core/dev-packages/pack-n-play/test/fixtures/esm-package/test/test.js b/core/dev-packages/pack-n-play/test/fixtures/esm-package/test/test.js
index 037babedf227..2adbf53d289c 100644
--- a/core/dev-packages/pack-n-play/test/fixtures/esm-package/test/test.js
+++ b/core/dev-packages/pack-n-play/test/fixtures/esm-package/test/test.js
@@ -16,7 +16,8 @@ import {packNTest} from 'pack-n-play';
 import * as assert from 'assert';
 import {describe, it} from 'mocha';
 
-describe('ESM package', () => {
+describe('ESM package', function () {
+  this.timeout(120000);
   it('should support esm property', () =>
     packNTest({
       sample: {
diff --git a/core/dev-packages/pack-n-play/test/fixtures/leaky/test/test.ts b/core/dev-packages/pack-n-play/test/fixtures/leaky/test/test.ts
index 3a9dc7f39b39..9c56bc9c0741 100644
--- a/core/dev-packages/pack-n-play/test/fixtures/leaky/test/test.ts
+++ b/core/dev-packages/pack-n-play/test/fixtures/leaky/test/test.ts
@@ -16,7 +16,8 @@ import {packNTest} from 'pack-n-play';
 import * as assert from 'assert';
 import {describe, it} from 'mocha';
 
-describe('leaky tests', () => {
+describe('leaky tests', function () {
+  this.timeout(120000);
   it('should fail packing n testing', async () => {
     await assert.rejects(
       packNTest({
diff --git a/core/dev-packages/pack-n-play/test/fixtures/pass/test/test.ts b/core/dev-packages/pack-n-play/test/fixtures/pass/test/test.ts
index 2dd02fb27cff..50d0d07d620d 100644
--- a/core/dev-packages/pack-n-play/test/fixtures/pass/test/test.ts
+++ b/core/dev-packages/pack-n-play/test/fixtures/pass/test/test.ts
@@ -15,7 +15,8 @@
 import {packNTest} from 'pack-n-play';
 import {describe, it} from 'mocha';
 
-describe('passing tests', () => {
+describe('passing tests', function () {
+  this.timeout(120000);
   it('should pass the test', async () => {
     await packNTest({
       sample: {
diff --git a/core/dev-packages/pack-n-play/test/test.ts b/core/dev-packages/pack-n-play/test/test.ts
index da954b94ba08..06aef544b4e7 100644
--- a/core/dev-packages/pack-n-play/test/test.ts
+++ b/core/dev-packages/pack-n-play/test/test.ts
@@ -18,7 +18,8 @@ import execa = require('execa');
 import {describe, it} from 'mocha';
 
 describe('pack-n-play', () => {
-  it('should run tests', async () => {
+  it('should run tests', async function () {
+    this.timeout(600000); // 10 minutes
     const fixturesPath = path.resolve('./test/fixtures');
     const dirs = fs
       .readdirSync(fixturesPath)
@@ -29,7 +30,7 @@ describe('pack-n-play', () => {
         stdio: 'inherit',
         cwd: dir,
       };
-      await execa('npm', ['install'], opts);
+      await execa('npm', ['install', '--no-audit', '--no-fund'], opts);
       await execa('npm', ['link', '../../../'], opts);
       await execa('npm', ['test'], opts);
     }