diff --git a/packages/vitec/Classes/Headless/ProcessedFileReferenceToArray.php b/packages/vitec/Classes/Headless/ProcessedFileReferenceToArray.php
new file mode 100644
index 0000000..8771ea4
--- /dev/null
+++ b/packages/vitec/Classes/Headless/ProcessedFileReferenceToArray.php
@@ -0,0 +1,105 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Evomedien\Vitec\Headless;
+
+use Netzbewegung\NbHeadlessContentBlocks\DataProcessing\ToArray\FileReferenceToArray;
+use TYPO3\CMS\Core\Imaging\ImageManipulation\CropVariantCollection;
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Extbase\Service\ImageService;
+
+/**
+ * XCLASS of the headless-content-blocks file serializer: delivers
+ * processed, responsive images instead of the original upload.
+ *
+ * Why (Lighthouse 2026-11-10, home page score 40 / LCP 25 s / 42 MB): the
+ * stock serializer emits `publicUrl` = the ORIGINAL file for every
+ * content-block image field (hero_bgimage, intro_image, card images …).
+ * Editors upload 4-13 MB JPEGs, so that is what every visitor downloads -
+ * while news/product images already go through the ImageService.
+ *
+ * Output per image (additive to the stock keys id/alt/title):
+ *  - publicUrl: now the processed default variant (WebP, max. 1920 px wide,
+ *    editor crop applied) - the frontend needs no change to benefit.
+ *  - originalUrl: the untouched upload, should anyone need it.
+ *  - srcset: WebP steps 480-1920 px (steps that would fall back to the
+ *    original are skipped), as {url,width,descriptor} like elsewhere.
+ *  - width/height: pixel size of the default variant (aspect ratio for
+ *    CLS-free layout) - mimeType alongside.
+ * Non-images (video, pdf …), SVG and GIF keep the stock behaviour and only
+ * gain mimeType/size (GIF processing would drop animation; SVG scales).
+ *
+ * Exception-safe: any processing failure falls back to the stock output.
+ */
+class ProcessedFileReferenceToArray extends FileReferenceToArray
+{
+    private const DEFAULT_WIDTH = 1920;
+    private const SRCSET_WIDTHS = [480, 768, 1024, 1440, 1920];
+    private const SKIP_EXTENSIONS = ['svg', 'gif'];
+
+    public function toArray(): array
+    {
+        $data = parent::toArray();
+
+        try {
+            $file = $this->fileReference;
+            $mimeType = (string)$file->getMimeType();
+            $extension = strtolower((string)$file->getExtension());
+
+            $data['mimeType'] = $mimeType;
+            $data['size'] = (int)$file->getSize();
+
+            if (!str_starts_with($mimeType, 'image/') || in_array($extension, self::SKIP_EXTENSIONS, true)) {
+                if (str_starts_with($mimeType, 'image/')) {
+                    $data['width'] = (int)$file->getProperty('width');
+                    $data['height'] = (int)$file->getProperty('height');
+                }
+                return $data;
+            }
+
+            $crop = null;
+            if ($file->hasProperty('crop') && $file->getProperty('crop')) {
+                $cropArea = CropVariantCollection::create((string)$file->getProperty('crop'))->getCropArea('default');
+                if (!$cropArea->isEmpty()) {
+                    $crop = $cropArea->makeAbsoluteBasedOnFile($file);
+                }
+            }
+
+            $imageService = GeneralUtility::makeInstance(ImageService::class);
+            $instructions = static fn (int $width): array => array_filter([
+                'width' => $width,
+                'crop' => $crop,
+                'fileExtension' => 'webp',
+            ], static fn ($v) => $v !== null);
+
+            $default = $imageService->applyProcessingInstructions($file, $instructions(self::DEFAULT_WIDTH));
+
+            $srcset = [];
+            foreach (self::SRCSET_WIDTHS as $width) {
+                $variant = $imageService->applyProcessingInstructions($file, $instructions($width));
+                if ($variant->usesOriginalFile()) {
+                    continue;
+                }
+                $srcset[] = [
+                    'url' => $imageService->getImageUri($variant, true),
+                    'width' => (int)$variant->getProperty('width'),
+                    'descriptor' => (int)$variant->getProperty('width') . 'w',
+                ];
+            }
+
+            $data['originalUrl'] = (string)($data['publicUrl'] ?? '');
+            $data['originalSize'] = (int)$file->getSize();
+            $data['publicUrl'] = $imageService->getImageUri($default, true);
+            $data['width'] = (int)$default->getProperty('width');
+            $data['height'] = (int)$default->getProperty('height');
+            $data['size'] = (int)$default->getSize();
+            $data['srcset'] = $srcset;
+            $data['mimeType'] = (string)($default->getMimeType() ?: 'image/webp');
+        } catch (\Throwable $e) {
+            // keep the stock payload
+        }
+
+        return $data;
+    }
+}
diff --git a/packages/vitec/ext_localconf.php b/packages/vitec/ext_localconf.php
index aa49d07..90ad5be 100755
--- a/packages/vitec/ext_localconf.php
+++ b/packages/vitec/ext_localconf.php
@@ -20,6 +20,14 @@ $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tcemain.php']['proc
 
 // XClass BackendLayoutView so the page module always reflects pages.layout
 // without the editor having to set backend_layout manually.
+// Content-block images as processed, responsive WebP instead of the raw
+// upload (Lighthouse 2026-11-10: 4-13 MB hero originals). The headless
+// content-blocks package instantiates its serializer via makeInstance, so
+// XCLASS is the supported hook. See Classes/Headless/ProcessedFileReferenceToArray.
+$GLOBALS['TYPO3_CONF_VARS']['SYS']['Objects'][\Netzbewegung\NbHeadlessContentBlocks\DataProcessing\ToArray\FileReferenceToArray::class] = [
+    'className' => \Evomedien\Vitec\Headless\ProcessedFileReferenceToArray::class,
+];
+
 $GLOBALS['TYPO3_CONF_VARS']['SYS']['Objects'][\TYPO3\CMS\Backend\View\BackendLayoutView::class] = [
     'className' => \Evomedien\Vitec\View\VitecBackendLayoutView::class,
 ];
diff --git a/public/.htaccess b/public/.htaccess
index bfb124d..3b7dc13 100644
--- a/public/.htaccess
+++ b/public/.htaccess
@@ -106,6 +106,19 @@
 
 
 
+### Begin: Immutable processed images (SEO/Lighthouse 2026-11-10) ###
+
+# Files below fileadmin/_processed_/ carry a content hash in their name and
+# never change in place - a year of immutable caching is safe and removes the
+# "uses-long-cache-ttl" findings (mod_expires below sets only one month).
+<IfModule mod_headers.c>
+	<If "%{REQUEST_URI} =~ m#^/fileadmin/_processed_/#">
+		Header set Cache-Control "max-age=31536000, immutable"
+	</If>
+</IfModule>
+
+### End: Immutable processed images ###
+
 ### Begin: Browser caching of resource files ###
 
 # This affects Frontend and Backend and increases performance.