diff --git a/public/index.html b/public/index.html
index 3c3c03a..0fa0e94 100644
--- a/public/index.html
+++ b/public/index.html
@@ -734,10 +734,10 @@
         </symbol>
     </svg>
     <!-- Scripts -->
-    <script src="scripts/localization.js"></script>
-    <script src="scripts/persistent-storage.js"></script>
-    <script src="scripts/ui-main.js"></script>
-    <script src="scripts/main.js"></script>
+    <script src="scripts/localization.js" defer></script>
+    <script src="scripts/persistent-storage.js" defer></script>
+    <script src="scripts/ui-main.js" defer></script>
+    <script src="scripts/main.js" defer></script>
     <!-- Sounds -->
     <audio id="blop" autobuffer="true">
         <source src="sounds/blop.mp3" type="audio/mpeg">
diff --git a/public/scripts/localization.js b/public/scripts/localization.js
index b696ef9..d81d3e3 100644
--- a/public/scripts/localization.js
+++ b/public/scripts/localization.js
@@ -1,40 +1,49 @@
 class Localization {
     constructor() {
+        Localization.$htmlRoot = document.querySelector('html');
+
         Localization.defaultLocale = "en";
         Localization.supportedLocales = ["ar", "ca", "de", "en", "es", "fr", "id", "it", "ja", "nb", "nl", "pt-BR", "ro", "ru", "tr", "zh-CN"];
         Localization.supportedLocalesRtl = ["ar"];
 
         Localization.translations = {};
-        Localization.defaultTranslations = {};
+        Localization.translationsDefaultLocale = {};
 
-        Localization.systemLocale = Localization.getSupportedOrDefault(navigator.languages);
+        Localization.systemLocale = Localization.getSupportedOrDefaultLocales(navigator.languages);
 
         let storedLanguageCode = localStorage.getItem('language_code');
 
-        Localization.initialLocale = storedLanguageCode && Localization.isSupported(storedLanguageCode)
+        Localization.initialLocale = storedLanguageCode && Localization.localeIsSupported(storedLanguageCode)
             ? storedLanguageCode
             : Localization.systemLocale;
     }
 
-    static isSupported(locale) {
+    static localeIsSupported(locale) {
         return Localization.supportedLocales.indexOf(locale) > -1;
     }
 
-    static isRtlLanguage(locale) {
+    static localeIsRtl(locale) {
         return Localization.supportedLocalesRtl.indexOf(locale) > -1;
     }
 
-    static isCurrentLocaleRtl() {
-        return Localization.isRtlLanguage(Localization.locale);
+    static currentLocaleIsRtl() {
+        return Localization.localeIsRtl(Localization.locale);
     }
 
-    static getSupportedOrDefault(locales) {
+    static currentLocaleIsDefault() {
+        return Localization.locale === Localization.defaultLocale
+    }
+
+    static getSupportedOrDefaultLocales(locales) {
+        // get generic locales not included in locales
+        // ["en-us", "de-CH", "fr"] --> ["en", "de"]
         let localesGeneric = locales
             .map(locale => locale.split("-")[0])
             .filter(locale => locales.indexOf(locale) === -1);
 
-        return locales.find(Localization.isSupported)
-            || localesGeneric.find(Localization.isSupported)
+        // If there is no perfect match for browser locales, try generic locales first before resorting to the default locale
+        return locales.find(Localization.localeIsSupported)
+            || localesGeneric.find(Localization.localeIsSupported)
             || Localization.defaultLocale;
     }
 
@@ -48,16 +57,14 @@ class Localization {
         await Localization.setLocale(locale)
         await Localization.translatePage();
 
-        const htmlRootNode = document.querySelector('html');
-
-        if (Localization.isRtlLanguage(locale)) {
-            htmlRootNode.setAttribute('dir', 'rtl');
+        if (Localization.localeIsRtl(locale)) {
+            Localization.$htmlRoot.setAttribute('dir', 'rtl');
         }
         else {
-            htmlRootNode.removeAttribute('dir');
+            Localization.$htmlRoot.removeAttribute('dir');
         }
 
-        htmlRootNode.setAttribute('lang', locale);
+        Localization.$htmlRoot.setAttribute('lang', locale);
 
 
         console.log("Page successfully translated",
@@ -111,75 +118,108 @@ class Localization {
         const key = element.getAttribute("data-i18n-key");
         const attrs = element.getAttribute("data-i18n-attrs").split(" ");
 
-        for (let i in attrs) {
-            let attr = attrs[i];
+        attrs.forEach(attr => {
             if (attr === "text") {
                 element.innerText = Localization.getTranslation(key);
             }
             else {
                 element.setAttribute(attr, Localization.getTranslation(key, attr));
             }
-        }
+        })
     }
 
-    static getTranslation(key, attr = null, data = {}, useDefault = false) {
-        const keys = key.split(".");
-
-        let translationCandidates = useDefault
-            ? Localization.defaultTranslations
-            : Localization.translations;
-
+    static getTranslationFromTranslationsObj(translationObj, key, attr) {
         let translation;
-
         try {
+            const keys = key.split(".");
+
             for (let i = 0; i < keys.length - 1; i++) {
-                translationCandidates = translationCandidates[keys[i]]
+                // iterate into translation object until last layer
+                translationObj = translationObj[keys[i]]
             }
 
             let lastKey = keys[keys.length - 1];
 
             if (attr) lastKey += "_" + attr;
 
-            translation = translationCandidates[lastKey];
+            translation = translationObj[lastKey];
 
-            for (let j in data) {
-                if (translation.includes(`{{${j}}}`)) {
-                    translation = translation.replace(`{{${j}}}`, data[j]);
-                } else {
-                    console.warn(`Translation for your language ${Localization.locale.toUpperCase()} misses at least one data placeholder:`, key, attr, data);
-                    Localization.logHelpCallKey(key);
-                    Localization.logHelpCall();
-                    translation = "";
-                    break;
-                }
-            }
         } catch (e) {
             console.error(e);
-            translation = "";
         }
 
         if (!translation) {
-            if (!useDefault) {
-                console.warn(`Missing translation entry for your language ${Localization.locale.toUpperCase()}. Using ${Localization.defaultLocale.toUpperCase()} instead.`, key, attr);
-                Localization.logHelpCallKey(key);
-                Localization.logHelpCall();
-                translation = this.getTranslation(key, attr, data, true);
+            throw new Error(`Translation misses entry. Key: ${key} Attribute: ${attr}`);
+        }
+
+        return translation;
+    }
+
+    static addDataToTranslation(translation, data) {
+        for (let j in data) {
+            if (!translation.includes(`{{${j}}}`)) {
+                throw new Error(`Translation misses data placeholder: ${j}`);
+            }
+            // Add data to translation
+            translation = translation.replace(`{{${j}}}`, data[j]);
+        }
+        return translation;
+    }
+
+    static getTranslation(key, attr = null, data = {}, useDefault = false) {
+        let translationObj = useDefault
+            ? Localization.translationsDefaultLocale
+            : Localization.translations;
+
+        let translation;
+
+        try {
+            translation = Localization.getTranslationFromTranslationsObj(translationObj, key, attr);
+            translation = Localization.addDataToTranslation(translation, data);
+        }
+        catch (e) {
+            // Log warnings and help calls
+            console.warn(e);
+            Localization.logTranslationMissingOrBroken(key, attr, data, useDefault);
+            Localization.logHelpCallKey(key, attr);
+            Localization.logHelpCall();
+
+            if (useDefault || Localization.currentLocaleIsDefault()) {
+                // Is default locale already
+                // Use empty string as translation
+                translation = ""
             }
             else {
-                console.warn("Missing translation in default language:", key, attr);
-                Localization.logHelpCall();
+                // Is not default locale yet
+                // Get translation for default language with same arguments
+                console.log(`Using default language ${Localization.defaultLocale.toUpperCase()} instead.`);
+                translation = this.getTranslation(key, attr, data, true);
             }
         }
 
         return Localization.escapeHTML(translation);
     }
 
+    static logTranslationMissingOrBroken(key, attr, data, useDefault) {
+        let usedLocale = useDefault
+            ? Localization.defaultLocale.toUpperCase()
+            : Localization.locale.toUpperCase();
+
+        console.warn(`Missing or broken translation for language ${usedLocale}.\n`, 'key:', key, 'attr:', attr, 'data:', data);
+    }
+
     static logHelpCall() {
         console.log("Help translating PairDrop: https://hosted.weblate.org/engage/pairdrop/");
     }
 
-    static logHelpCallKey(key) {
-        console.warn(`Translate this string here: https://hosted.weblate.org/browse/pairdrop/pairdrop-spa/${Localization.locale.toLowerCase()}/?q=${key}`);
+    static logHelpCallKey(key, attr) {
+        let locale = Localization.locale.toLowerCase();
+
+        let keyComplete = !attr || attr === "text"
+            ? key
+            : `${key}_${attr}`;
+
+        console.warn(`Translate this string here: https://hosted.weblate.org/browse/pairdrop/pairdrop-spa/${locale}/?q=${keyComplete}`);
     }
 
     static escapeHTML(unsafeText) {
diff --git a/public/scripts/main.js b/public/scripts/main.js
index e6ff259..8960ed2 100644
--- a/public/scripts/main.js
+++ b/public/scripts/main.js
@@ -56,13 +56,16 @@ class PairDrop {
         await this.backgroundCanvas.fadeIn();
 
         // Load deferred assets
+        console.log("Load deferred assets...");
         await this.loadDeferredAssets();
         console.log("Loading of deferred assets completed.");
 
+        console.log("Hydrate UI...");
         await this.hydrate();
         console.log("UI hydrated.");
 
         // Evaluate url params as soon as ws is connected
+        console.log("Evaluate URL params as soon as websocket connection is established.");
         Events.on('ws-connected', _ => this.evaluateUrlParams(), {once: true});
     }
 
@@ -102,36 +105,40 @@ class PairDrop {
         }
     }
 
-    async loadDeferredAssets() {
-        console.log("Load deferred assets");
-        for (const url of this.deferredStyles) {
-            await this.loadAndApplyStylesheet(url);
-        }
-        for (const url of this.deferredScripts) {
-            await this.loadAndApplyScript(url);
-        }
+    loadDeferredAssets() {
+        const stylePromises = this.deferredStyles.map(url => this.loadAndApplyStylesheet(url));
+        const scriptPromises = this.deferredScripts.map(url => this.loadAndApplyScript(url));
+
+        return Promise.all([...stylePromises, ...scriptPromises]);
     }
 
     loadStyleSheet(url) {
         return new Promise((resolve, reject) => {
             let stylesheet = document.createElement('link');
-            stylesheet.rel = 'stylesheet';
+            stylesheet.rel = 'preload';
+            stylesheet.as = 'style';
             stylesheet.href = url;
-            stylesheet.type = 'text/css';
-            stylesheet.onload = resolve;
+            stylesheet.onload = _ => {
+                stylesheet.onload = null;
+                stylesheet.rel = 'stylesheet';
+                resolve();
+            };
             stylesheet.onerror = reject;
 
             document.head.appendChild(stylesheet);
         });
     }
 
-    async loadAndApplyStylesheet(url) {
-        try {
-            await this.loadStyleSheet(url);
-            console.log(`Stylesheet loaded successfully: ${url}`);
-        } catch (error) {
-            console.error('Error loading stylesheet:', error);
-        }
+    loadAndApplyStylesheet(url) {
+        return new Promise( async (resolve) => {
+            try {
+                await this.loadStyleSheet(url);
+                console.log(`Stylesheet loaded successfully: ${url}`);
+                resolve();
+            } catch (error) {
+                console.error('Error loading stylesheet:', error);
+            }
+        });
     }
 
     loadScript(url) {
@@ -145,13 +152,16 @@ class PairDrop {
         });
     }
 
-    async loadAndApplyScript(url) {
-        try {
-            await this.loadScript(url);
-            console.log(`Script loaded successfully: ${url}`);
-        } catch (error) {
-            console.error('Error loading script:', error);
-        }
+    loadAndApplyScript(url) {
+        return new Promise( async (resolve) => {
+            try {
+                await this.loadScript(url);
+                console.log(`Script loaded successfully: ${url}`);
+                resolve();
+            } catch (error) {
+                console.error('Error loading script:', error);
+            }
+        });
     }
 
     async hydrate() {
@@ -223,6 +233,8 @@ class PairDrop {
         // remove url params from url
         const urlWithoutParams = getUrlWithoutArguments();
         window.history.replaceState({}, "Rewrite URL", urlWithoutParams);
+
+        console.log("URL params evaluated.");
     }
 }
 
diff --git a/public/scripts/ui-main.js b/public/scripts/ui-main.js
index 409a29c..c7a27e5 100644
--- a/public/scripts/ui-main.js
+++ b/public/scripts/ui-main.js
@@ -132,7 +132,7 @@ class HeaderUI {
         this.$header.classList.remove('overflow-expanded');
 
 
-        const rtlLocale = Localization.isCurrentLocaleRtl();
+        const rtlLocale = Localization.currentLocaleIsRtl();
         let icon;
         const $headerIconsShown = document.querySelectorAll('body > header:first-of-type > *:not([hidden])');
 
diff --git a/public/scripts/ui.js b/public/scripts/ui.js
index 52fecbc..ae63a0e 100644
--- a/public/scripts/ui.js
+++ b/public/scripts/ui.js
@@ -2420,14 +2420,9 @@ class Notifications {
 
     _downloadNotification(files) {
         if (document.visibilityState !== 'visible') {
-            let imagesOnly = true;
-            for(let i=0; i<files.length; i++) {
-                if (files[i].type.split('/')[0] !== 'image') {
-                    imagesOnly = false;
-                    break;
-                }
-            }
+            let imagesOnly = files.every(file => file.type.split('/')[0] === 'image');
             let title;
+
             if (files.length === 1) {
                 title = `${files[0].name}`;
             }
@@ -2452,15 +2447,8 @@ class Notifications {
 
     _requestNotification(request, peerId) {
         if (document.visibilityState !== 'visible') {
-            let imagesOnly = true;
-            for(let i=0; i<request.header.length; i++) {
-                if (request.header[i].mime.split('/')[0] !== 'image') {
-                    imagesOnly = false;
-                    break;
-                }
-            }
-
-            let displayName = $(peerId).querySelector('.name').textContent
+            let imagesOnly = request.header.every(header => header.mime.split('/')[0] === 'image');
+            let displayName = $(peerId).querySelector('.name').textContent;
 
             let descriptor;
             if (request.header.length === 1) {
diff --git a/server/index.js b/server/index.js
index 2134c67..9f5d7b8 100644
--- a/server/index.js
+++ b/server/index.js
@@ -32,10 +32,14 @@ process.on('unhandledRejection', (reason, promise) => {
 
 // Evaluate arguments for deployment with Docker and Node.js
 let conf = {};
+
 conf.debugMode = process.env.DEBUG_MODE === "true";
+
 conf.port = process.env.PORT || 3000;
+
 conf.wsFallback = process.argv.includes('--include-ws-fallback') || process.env.WS_FALLBACK === "true";
-conf.rtcConfig = process.env.RTC_CONFIG
+
+conf.rtcConfig = process.env.RTC_CONFIG && process.env.RTC_CONFIG !== "false"
     ? JSON.parse(fs.readFileSync(process.env.RTC_CONFIG, 'utf8'))
     : {
         "sdpSemantics": "unified-plan",
@@ -47,7 +51,10 @@ conf.rtcConfig = process.env.RTC_CONFIG
     };
 
 
-conf.signalingServer = process.env.SIGNALING_SERVER || false;
+conf.signalingServer = process.env.SIGNALING_SERVER && process.env.SIGNALING_SERVER !== "false"
+    ? process.env.SIGNALING_SERVER
+    : false;
+
 conf.ipv6Localize = parseInt(process.env.IPV6_LOCALIZE) || false;
 
 let rateLimit = false;
@@ -61,6 +68,7 @@ else {
     }
 }
 conf.rateLimit = rateLimit;
+
 conf.buttons = {
     "donation_button": {
         "active": process.env.DONATION_BUTTON_ACTIVE,
@@ -96,8 +104,10 @@ conf.buttons = {
 
 // Evaluate arguments for deployment with Node.js only
 conf.autoStart = process.argv.includes('--auto-restart');
+
 conf.localhostOnly = process.argv.includes('--localhost-only');
 
+
 // Validate configuration
 if (conf.ipv6Localize) {
     if (!(0 < conf.ipv6Localize && conf.ipv6Localize < 8)) {