diff --git a/api/applyEffects.php b/api/applyEffects.php
index 1525711f6..b8913225e 100644
--- a/api/applyEffects.php
+++ b/api/applyEffects.php
@@ -125,14 +125,39 @@
             }
 
             if (!$vars['isCollage'] || $vars['editSingleCollage']) {
-                // apply filter
+                // apply filter (optionally downscale first for performance)
                 if ($vars['imageFilter'] !== null && $vars['imageFilter'] !== ImageFilterEnum::PLAIN) {
+                    $originalWidth = imagesx($imageResource);
+                    $originalHeight = imagesy($imageResource);
+                    $filterResource = $imageResource;
+
+                    $filterProcessSize = intval($config['filters']['process_size'] ?? 0);
+                    if ($filterProcessSize > 0 && ($originalWidth > $filterProcessSize || $originalHeight > $filterProcessSize)) {
+                        $downscaled = $imageHandler->resizeImage($imageResource, $filterProcessSize);
+                        if ($downscaled instanceof \GdImage) {
+                            $filterResource = $downscaled;
+                        }
+                    }
+
                     try {
-                        ImageUtility::applyFilter($vars['imageFilter'], $imageResource);
+                        ImageUtility::applyFilter($vars['imageFilter'], $filterResource);
                         $imageHandler->imageModified = true;
                     } catch (\Exception $e) {
                         throw new \Exception('Error applying image filter.');
                     }
+
+                    if ($filterResource !== $imageResource) {
+                        $imageResource = $filterResource;
+                        // Maybe we want this later or configurable, will take some time to process upscale again
+                        // Upscale back to original size
+                        //                        $restored = $imageHandler->resizeImage($filterResource, $originalWidth, $originalHeight);
+                        //                        if ($restored instanceof \GdImage) {
+                        //                            if ($filterResource instanceof \GdImage) {
+                        //                                unset($filterResource);
+                        //                            }
+                        //                            $imageResource = $restored;
+                        //                        }
+                    }
                 }
 
                 if ($config['picture']['flip'] !== 'off') {
diff --git a/assets/js/core.js b/assets/js/core.js
index b2bf638e7..5e3196023 100644
--- a/assets/js/core.js
+++ b/assets/js/core.js
@@ -67,6 +67,7 @@ const photoBooth = (function () {
         chromaFile = '',
         currentCollageFile = '',
         imgFilter = config.filters.defaults,
+        isProcessingEffects = false,
         command,
         startTime,
         endTime,
@@ -91,7 +92,7 @@ const photoBooth = (function () {
         photoboothTools.console.log('Timeout for auto reload cleared.');
 
         if (!api.takingPic) {
-            photoboothTools.console.logDev('Timeout for auto reload set to' + timeToLive + ' milliseconds.');
+            photoboothTools.console.logDev('Timeout for auto reload set to ' + timeToLive + ' milliseconds.');
             timeOut = setTimeout(function () {
                 photoboothTools.reloadPage();
             }, timeToLive);
@@ -154,6 +155,12 @@ const photoBooth = (function () {
         }
     };
 
+    const setFiltersEnabled = (enabled) => {
+        isProcessingEffects = !enabled;
+        filternav.css('pointer-events', enabled ? '' : 'none');
+        filternav.toggleClass('filters--disabled', !enabled);
+    };
+
     api.stopPreviewAndCaptureFromVideo = () => {
         if (config.preview.camTakesPic) {
             if (photoboothPreview.stream) {
@@ -811,6 +818,7 @@ const photoBooth = (function () {
         setTimeout(function () {
             api.cheese.destroy();
             api.shutter.destroy();
+            setFiltersEnabled(true);
 
             loaderMessage.empty();
             loaderButtonBar.empty();
@@ -850,6 +858,10 @@ const photoBooth = (function () {
 
     api.processPic = function (result) {
         startTime = new Date().getTime();
+        loader.addClass('stage--active');
+        startPage.removeClass('stage--active');
+        resultPage.removeClass('stage--active');
+        setFiltersEnabled(false);
         loaderMessage.html(
             '<i class="' +
                 config.icons.spinner +
@@ -881,10 +893,13 @@ const photoBooth = (function () {
                 style: api.photoStyle
             },
             success: (data) => {
+                setFiltersEnabled(true);
                 photoboothTools.console.log(api.photoStyle + ' processed', data);
                 endTime = new Date().getTime();
                 totalTime = endTime - startTime;
-                photoboothTools.console.logDev('Processing ' + api.photoStyle + ' took ' + totalTime + 'ms');
+                photoboothTools.console.logDev(
+                    'Processing ' + api.photoStyle + ' took ' + totalTime + 'ms for filter `' + imgFilter + '`'
+                );
                 photoboothTools.console.logDev('Images:', data.images);
 
                 if (config.get_request.processed) {
@@ -901,6 +916,7 @@ const photoBooth = (function () {
                 }
             },
             error: (jqXHR, textStatus) => {
+                setFiltersEnabled(true);
                 api.errorPic({
                     error: 'Request failed: ' + textStatus
                 });
@@ -1360,6 +1376,10 @@ const photoBooth = (function () {
     });
 
     $('.sidenav-list-item[data-filter]').on('click', function () {
+        if (isProcessingEffects) {
+            photoboothTools.console.logDev('Ignoring filter click: processing in progress.');
+            return;
+        }
         $('.sidenav').find('.sidenav-list-item--active').removeClass('sidenav-list-item--active');
         $(this).addClass('sidenav-list-item--active');
 
diff --git a/assets/sass/components/_sidenav.scss b/assets/sass/components/_sidenav.scss
index eb988745f..42614dff3 100644
--- a/assets/sass/components/_sidenav.scss
+++ b/assets/sass/components/_sidenav.scss
@@ -73,6 +73,10 @@
   height: var(--sidenav-close-height);
   border: none;
   line-height: 1;
+  padding: 0;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
 
   &:hover {
     background: var(--highlight-color);
diff --git a/lib/configsetup.inc.php b/lib/configsetup.inc.php
index f634e88a7..a468f03f1 100644
--- a/lib/configsetup.inc.php
+++ b/lib/configsetup.inc.php
@@ -587,6 +587,17 @@
             'options' => ImageFilterEnum::cases(),
             'value' => $config['filters']['defaults'],
         ],
+        'filters_process_size' => [
+            'view' => 'expert',
+            'type' => 'range',
+            'name' => 'filters[process_size]',
+            'placeholder' => $defaultConfig['filters']['process_size'],
+            'value' => $config['filters']['process_size'],
+            'range_min' => 0,
+            'range_max' => 5000,
+            'range_step' => 50,
+            'unit' => 'px',
+        ],
         'filters_disabled' => [
             'view' => 'expert',
             'type' => 'multi-select',
diff --git a/resources/lang/de.json b/resources/lang/de.json
index 46f0b110f..185b9e055 100644
--- a/resources/lang/de.json
+++ b/resources/lang/de.json
@@ -517,6 +517,7 @@
   "manual:pictures:filters_defaults": "Wählen Sie einen Bildfilter, der standardmäßig nach der Aufnahme angewendet wird.",
   "manual:pictures:filters_disabled": "Wählen Sie Filter aus, die aus den verfügbaren Bildfiltern entfernt werden.",
   "manual:pictures:filters_enabled": "Wenn diese Option aktiviert ist, kann der Benutzer nach dem Aufnehmen eines Bildes einen Bildfilter auswählen.",
+  "manual:pictures:filters_process_size": "Bilder vor dem Filter auf diese maximale Breite/Höhe verkleinern, um die Verarbeitung zu beschleunigen. Auf 0 setzen, um zu deaktivieren.",
   "manual:pictures:picture_allow_delete": "Wenn diese Option aktiviert ist, können Bilder direkt nach der Aufnahme auf der Ergebnisseite gelöscht werden.",
   "manual:pictures:picture_cheese_time": "Legen Sie eine Zeit fest zur Anzeige von \"Cheeeeeeeese!\" nach dem Countdown.",
   "manual:pictures:picture_cntdwn_time": "Legen Sie Ihre Countdown-Zeit fest.",
@@ -740,6 +741,7 @@
   "pictures:filters_defaults": "Standardbildfilter",
   "pictures:filters_disabled": "Deaktivierte Bildfilter",
   "pictures:filters_enabled": "Bildfilter erlauben",
+  "pictures:filters_process_size": "Filter-Verarbeitungsgröße",
   "pictures:picture_allow_delete": "Löschen des Bildes erlauben",
   "pictures:picture_cheese_time": "Lächeln Timer:",
   "pictures:picture_cntdwn_time": "Countdown Timer:",
diff --git a/resources/lang/en.json b/resources/lang/en.json
index c7d4321ef..a722d3863 100644
--- a/resources/lang/en.json
+++ b/resources/lang/en.json
@@ -521,6 +521,7 @@
   "manual:pictures:filters_defaults": "Choose an image filter which is applied by default after taking a picture.",
   "manual:pictures:filters_disabled": "Choose filters which get removed from the available image filters.",
   "manual:pictures:filters_enabled": "If enabled, users can choose an image filter after taking a picture.",
+  "manual:pictures:filters_process_size": "Downscale images to this maximum width/height before applying filters to speed up processing. Set to 0 to disable.",
   "manual:pictures:picture_allow_delete": "If enabled pictures can be deleted on result page directly after they have been taken.",
   "manual:pictures:picture_cheese_time": "Set a time to display \"Cheeeeeeeese!\" after the countdown.",
   "manual:pictures:picture_cntdwn_time": "Set your countdown time.",
@@ -744,6 +745,7 @@
   "pictures:filters_defaults": "Default image filter",
   "pictures:filters_disabled": "Disabled image filters",
   "pictures:filters_enabled": "Allow image filter",
+  "pictures:filters_process_size": "Filter processing size",
   "pictures:picture_allow_delete": "Allow deletion of the image",
   "pictures:picture_cheese_time": "Cheese timer:",
   "pictures:picture_cntdwn_time": "Countdown timer:",
diff --git a/src/Configuration/Section/FilterConfiguration.php b/src/Configuration/Section/FilterConfiguration.php
index e9f19f2c3..e654c8935 100644
--- a/src/Configuration/Section/FilterConfiguration.php
+++ b/src/Configuration/Section/FilterConfiguration.php
@@ -28,6 +28,16 @@ public static function getNode(): NodeDefinition
                         })
                         ->end()
                     ->end()
+                ->integerNode('process_size')
+                    ->info('Downscale images to this maximum width/height before applying filters to speed up processing. Set to 0 to disable.')
+                    ->defaultValue(0)
+                    ->min(0)
+                    ->max(5000)
+                    ->beforeNormalization()
+                        ->ifString()
+                        ->then(function (string $value): int { return intval($value); })
+                        ->end()
+                    ->end()
                 ->arrayNode('disabled')
                     ->enumPrototype()
                         ->values(ImageFilterEnum::cases())