diff --git a/.gitea/actions/ci-lint-php/action.yml b/.gitea/actions/ci-lint-php/action.yml
index d831bb7..2e83a3b 100644
--- a/.gitea/actions/ci-lint-php/action.yml
+++ b/.gitea/actions/ci-lint-php/action.yml
@@ -6,7 +6,20 @@ inputs:
 runs:
   using: composite
   steps:
-    - name: Setup PHP ${{ inputs.php }}
+    - name: Use preinstalled PHP ${{ inputs.php }} (peptide-php image)
+      id: pre
+      shell: bash
+      env:
+        V: ${{ inputs.php }}
+      run: |
+        if command -v "php$V" >/dev/null 2>&1; then
+          update-alternatives --set php "/usr/bin/php$V" >/dev/null 2>&1 || ln -sf "/usr/bin/php$V" /usr/local/bin/php
+          php -v | head -1; echo "hit=true" >> "$GITHUB_OUTPUT"
+        else
+          echo "hit=false" >> "$GITHUB_OUTPUT"
+        fi
+    - name: Setup PHP ${{ inputs.php }} (fallback when not preinstalled)
+      if: ${{ steps.pre.outputs.hit != 'true' }}
       uses: shivammathur/setup-php@v2
       with:
         php-version: ${{ inputs.php }}
diff --git a/.gitea/actions/ci-phpcs/action.yml b/.gitea/actions/ci-phpcs/action.yml
index ab5b83e..c754002 100644
--- a/.gitea/actions/ci-phpcs/action.yml
+++ b/.gitea/actions/ci-phpcs/action.yml
@@ -10,7 +10,18 @@ inputs:
 runs:
   using: composite
   steps:
-    - name: Setup PHP
+    - name: Use preinstalled PHP 8.1 (peptide-php image)
+      id: pre
+      shell: bash
+      run: |
+        if command -v php8.1 >/dev/null 2>&1 && command -v composer >/dev/null 2>&1; then
+          update-alternatives --set php /usr/bin/php8.1 >/dev/null 2>&1 || ln -sf /usr/bin/php8.1 /usr/local/bin/php
+          php -v | head -1; echo "hit=true" >> "$GITHUB_OUTPUT"
+        else
+          echo "hit=false" >> "$GITHUB_OUTPUT"
+        fi
+    - name: Setup PHP (fallback when not preinstalled)
+      if: ${{ steps.pre.outputs.hit != 'true' }}
       uses: shivammathur/setup-php@v2
       with:
         php-version: '8.1'
@@ -27,6 +38,9 @@ runs:
           "wp-coding-standards/wpcs:^3.0" \
           "phpcsstandards/phpcsutils:^1.0" \
           "phpcsstandards/phpcsextra:^1.0"
+        # Without setup-php's `tools: phpcs`, phpcs/phpcbf come from the global
+        # composer bin dir (WPCS pulls in squizlabs/php_codesniffer).
+        composer global config bin-dir --absolute 2>/dev/null | tail -1 >> "$GITHUB_PATH"
 
     - name: Auto-fix with phpcbf (PR only, commit back if changed)
       if: ${{ github.event_name == 'pull_request' && inputs.autofix == 'true' }}
diff --git a/.gitea/actions/ci-phpunit/action.yml b/.gitea/actions/ci-phpunit/action.yml
index 704bd4d..758952e 100644
--- a/.gitea/actions/ci-phpunit/action.yml
+++ b/.gitea/actions/ci-phpunit/action.yml
@@ -21,7 +21,20 @@ runs:
       shell: bash
       run: command -v svn >/dev/null || (sudo apt-get update -qq && sudo apt-get install -y --no-install-recommends subversion)
 
-    - name: Setup PHP ${{ inputs.php }}
+    - name: Use preinstalled PHP ${{ inputs.php }} (peptide-php image)
+      id: pre
+      shell: bash
+      env:
+        V: ${{ inputs.php }}
+      run: |
+        if command -v "php$V" >/dev/null 2>&1 && command -v composer >/dev/null 2>&1; then
+          update-alternatives --set php "/usr/bin/php$V" >/dev/null 2>&1 || ln -sf "/usr/bin/php$V" /usr/local/bin/php
+          php -v | head -1; echo "hit=true" >> "$GITHUB_OUTPUT"
+        else
+          echo "hit=false" >> "$GITHUB_OUTPUT"
+        fi
+    - name: Setup PHP ${{ inputs.php }} (fallback when not preinstalled)
+      if: ${{ steps.pre.outputs.hit != 'true' }}
       uses: shivammathur/setup-php@v2
       with:
         php-version: ${{ inputs.php }}
diff --git a/.gitea/workflows/pipeline.yml b/.gitea/workflows/pipeline.yml
index 0978875..183d7a6 100644
--- a/.gitea/workflows/pipeline.yml
+++ b/.gitea/workflows/pipeline.yml
@@ -16,6 +16,7 @@ jobs:
   lint-php:
     name: PHP Lint (${{ matrix.php }})
     runs-on: ubuntu-latest
+    container: git.protopeer.com/peptide-repo/ci-php:2026-10
     strategy:
       fail-fast: false
       matrix:
@@ -29,6 +30,7 @@ jobs:
   phpcs:
     name: PHPCS (WordPress standards)
     runs-on: ubuntu-latest
+    container: git.protopeer.com/peptide-repo/ci-php:2026-10
     steps:
       - uses: actions/checkout@v4
         with:
diff --git a/ci-image/Dockerfile b/ci-image/Dockerfile
new file mode 100644
index 0000000..2bc0aa1
--- /dev/null
+++ b/ci-image/Dockerfile
@@ -0,0 +1,15 @@
+# peptide-ci-php: Gitea runner image with PHP 8.1/8.2/8.3 + Composer preinstalled.
+# Why: shivammathur/setup-php treats the stock runner image as a bare self-hosted
+# box and apt-installs a whole compiler toolchain on every job (~5-10 min each).
+# Built into the gitea-dind daemon by ci-image/build.sh; runner label `peptide-php`.
+FROM docker.gitea.com/runner-images@sha256:fd911d7417bfbf0f454530e447da95b58001e1df41bbc5e1a8dd35d432575aae
+RUN set -eux; export DEBIAN_FRONTEND=noninteractive; \
+    apt-get update; apt-get install -y --no-install-recommends software-properties-common gnupg unzip mariadb-client; \
+    add-apt-repository -y ppa:ondrej/php; apt-get update; \
+    for v in 8.1 8.2 8.3; do \
+      apt-get install -y --no-install-recommends php$v-cli php$v-common php$v-mbstring php$v-xml php$v-curl php$v-zip php$v-mysql php$v-intl php$v-bcmath php$v-gd; \
+    done; \
+    update-alternatives --set php /usr/bin/php8.3; \
+    curl -fsSL https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer; \
+    composer --version; php8.1 -v | head -1; php8.2 -v | head -1; php8.3 -v | head -1; \
+    rm -rf /var/lib/apt/lists/*
diff --git a/ci-image/build.sh b/ci-image/build.sh
new file mode 100755
index 0000000..d7ade4f
--- /dev/null
+++ b/ci-image/build.sh
@@ -0,0 +1,6 @@
+#!/bin/sh
+# Build peptide-ci-php into the gitea-dind daemon the shared runner uses.
+set -e
+TAG=peptide-ci-php:2026-10
+docker exec -i gitea-dind docker build -t "$TAG" - < "$(dirname "$0")/Dockerfile"
+docker exec gitea-dind docker image inspect "$TAG" --format '{{.Id}} {{.Size}}'
diff --git a/tools/gitea-pipeline/render.py b/tools/gitea-pipeline/render.py
index d739683..7c26073 100644
--- a/tools/gitea-pipeline/render.py
+++ b/tools/gitea-pipeline/render.py
@@ -12,6 +12,9 @@ import json
 import sys
 
 A = "https://git.protopeer.com/peptide-repo/peptide-e2e/.gitea/actions"
+# CI image with PHP 8.1/8.2/8.3 + Composer preinstalled (peptide-e2e/ci-image).
+# Without it setup-php bootstraps a compiler toolchain on every job (5-20 min).
+CI_IMAGE = "git.protopeer.com/peptide-repo/ci-php:2026-10"
 DEFAULTS = {"tests": "stubs", "has_js": False, "line_limit_paths": "includes",
             "enforce_300": True, "phpcs_autofix": True, "audit": True,
             "php_versions": ["8.1", "8.2", "8.3"], "extras": []}
@@ -24,10 +27,8 @@ EXTRAS = {
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: shivammathur/setup-php@v2
-        with:
-          php-version: '8.1'
-          coverage: none
+      - name: Use PHP 8.1 (preinstalled in the CI image)
+        run: update-alternatives --set php /usr/bin/php8.1 && php -v | head -1
       # Fails if any PRAUTOBLOGGER_* constant referenced in shipped PHP is neither
       # defined in prautoblogger.php nor guarded by defined() (v0.19.0 incident class).
       - run: php scripts/check-constants.php
@@ -244,7 +245,9 @@ jobs:
         with:
           token: ${{{{ secrets.GITHUB_TOKEN }}}}
 """)
-    return "".join(out)
+    return "".join(out).replace(
+        "    runs-on: ubuntu-latest\n",
+        f"    runs-on: ubuntu-latest\n    container: {CI_IMAGE}\n")
 
 
 if __name__ == "__main__":