diff --git a/CHANGELOG.md b/CHANGELOG.md
index e58069e..98c690f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+## [1.5.3](https://github.com/adobe/aem-lib/compare/v1.5.2...v1.5.3) (2024-04-17)
+
+
+### Bug Fixes
+
+* **package): Revert "fix(deps:** update dependency @adobe/helix-rum-js to v2" ([a0a54a9](https://github.com/adobe/aem-lib/commit/a0a54a93e6c4fb2ba9e2405e51f9535967121dc5))
+
 ## [1.5.2](https://github.com/adobe/aem-lib/compare/v1.5.1...v1.5.2) (2024-04-17)
 
 
diff --git a/dist/aem.js b/dist/aem.js
index 2bff8f0..3aef990 100644
--- a/dist/aem.js
+++ b/dist/aem.js
@@ -11,63 +11,135 @@
  */
 
 /* eslint-env browser */
-function sampleRUM(checkpoint, data) {
-  // eslint-disable-next-line max-len
-  const timeShift = () => (window.performance ? window.performance.now() : Date.now() - window.hlx.rum.firstReadTime);
+
+/**
+ * log RUM if part of the sample.
+ * @param {string} checkpoint identifies the checkpoint in funnel
+ * @param {Object} data additional data for RUM sample
+ * @param {string} data.source DOM node that is the source of a checkpoint event,
+ * identified by #id or .classname
+ * @param {string} data.target subject of the checkpoint event,
+ * for instance the href of a link, or a search term
+ */
+function sampleRUM(checkpoint, data = {}) {
   const SESSION_STORAGE_KEY = 'aem-rum';
+  sampleRUM.baseURL = sampleRUM.baseURL
+    || new URL(window.RUM_BASE == null ? 'https://rum.hlx.page' : window.RUM_BASE, window.location);
+  sampleRUM.defer = sampleRUM.defer || [];
+  const defer = (fnname) => {
+    sampleRUM[fnname] = sampleRUM[fnname] || ((...args) => sampleRUM.defer.push({ fnname, args }));
+  };
+  sampleRUM.drain = sampleRUM.drain
+    || ((dfnname, fn) => {
+      sampleRUM[dfnname] = fn;
+      sampleRUM.defer
+        .filter(({ fnname }) => dfnname === fnname)
+        .forEach(({ fnname, args }) => sampleRUM[fnname](...args));
+    });
+  sampleRUM.always = sampleRUM.always || [];
+  sampleRUM.always.on = (chkpnt, fn) => {
+    sampleRUM.always[chkpnt] = fn;
+  };
+  sampleRUM.on = (chkpnt, fn) => {
+    sampleRUM.cases[chkpnt] = fn;
+  };
+  defer('observe');
+  defer('cwv');
   try {
     window.hlx = window.hlx || {};
     if (!window.hlx.rum) {
-      // eslint-disable-next-line max-len
-      const rumStorage = sessionStorage.getItem(SESSION_STORAGE_KEY)
-        ? JSON.parse(sessionStorage.getItem(SESSION_STORAGE_KEY))
-        : {};
-      rumStorage.pages = (rumStorage.pages ?? 0) + (Math.floor(Math.random() * 20) - 10) + 1;
-      sessionStorage.setItem(SESSION_STORAGE_KEY, JSON.stringify(rumStorage));
-      sampleRUM.baseURL = sampleRUM.baseURL
-        || new URL(
-          window.RUM_BASE == null ? 'https://rum.hlx.page' : window.RUM_BASE,
-          window.location,
-        );
-      const weight = new URLSearchParams(window.location.search).get('rum') === 'on' ? 1 : 100;
+      const usp = new URLSearchParams(window.location.search);
+      const weight = usp.get('rum') === 'on' ? 1 : 100; // with parameter, weight is 1. Defaults to 100.
       const id = Array.from({ length: 75 }, (_, i) => String.fromCharCode(48 + i))
         .filter((a) => /\d|[A-Z]/i.test(a))
         .filter(() => Math.random() * 75 > 70)
         .join('');
-      const isSelected = Math.random() * weight < 1;
+      const random = Math.random();
+      const isSelected = random * weight < 1;
+      const firstReadTime = window.performance ? window.performance.timeOrigin : Date.now();
+      const urlSanitizers = {
+        full: () => window.location.href,
+        origin: () => window.location.origin,
+        path: () => window.location.href.replace(/\?.*$/, ''),
+      };
+      // eslint-disable-next-line max-len
+      const rumSessionStorage = sessionStorage.getItem(SESSION_STORAGE_KEY)
+        ? JSON.parse(sessionStorage.getItem(SESSION_STORAGE_KEY))
+        : {};
+      // eslint-disable-next-line max-len
+      rumSessionStorage.pages = (rumSessionStorage.pages ? rumSessionStorage.pages : 0)
+        + 1
+        /* noise */ + (Math.floor(Math.random() * 20) - 10);
+      sessionStorage.setItem(SESSION_STORAGE_KEY, JSON.stringify(rumSessionStorage));
       // eslint-disable-next-line object-curly-newline, max-len
       window.hlx.rum = {
         weight,
         id,
+        random,
         isSelected,
-        firstReadTime: window.performance ? window.performance.timeOrigin : Date.now(),
+        firstReadTime,
         sampleRUM,
-        queue: [],
-        collector: (...args) => window.hlx.rum.queue.push(args),
+        sanitizeURL: urlSanitizers[window.hlx.RUM_MASK_URL || 'path'],
+        rumSessionStorage,
       };
-      if (isSelected) {
-        // eslint-disable-next-line object-curly-newline, max-len
-        const body = JSON.stringify({
-          weight,
-          id,
-          referer: window.location.href,
-          checkpoint: 'top',
-          t: timeShift(),
-          target: document.visibilityState,
-        });
+    }
+
+    const { weight, id, firstReadTime } = window.hlx.rum;
+    if (window.hlx && window.hlx.rum && window.hlx.rum.isSelected) {
+      const knownProperties = [
+        'weight',
+        'id',
+        'referer',
+        'checkpoint',
+        't',
+        'source',
+        'target',
+        'cwv',
+        'CLS',
+        'FID',
+        'LCP',
+        'INP',
+        'TTFB',
+      ];
+      const sendPing = (pdata = data) => {
+        // eslint-disable-next-line max-len
+        const t = Math.round(
+          window.performance ? window.performance.now() : Date.now() - firstReadTime,
+        );
+        // eslint-disable-next-line object-curly-newline, max-len, no-use-before-define
+        const body = JSON.stringify(
+          {
+            weight, id, referer: window.hlx.rum.sanitizeURL(), checkpoint, t, ...data,
+          },
+          knownProperties,
+        );
         const url = new URL(`.rum/${weight}`, sampleRUM.baseURL).href;
         navigator.sendBeacon(url, body);
-        // eslint-disable-next-line max-statements-per-line, brace-style
-        window.addEventListener('load', () => {
-          sampleRUM('load');
-          import(new URL('.rum/@adobe/helix-rum-enhancer@^2/src/index.js', sampleRUM.baseURL));
-        });
+        // eslint-disable-next-line no-console
+        console.debug(`ping:${checkpoint}`, pdata);
+      };
+      sampleRUM.cases = sampleRUM.cases || {
+        load: () => sampleRUM('pagesviewed', { source: window.hlx.rum.rumSessionStorage.pages }) || true,
+        cwv: () => sampleRUM.cwv(data) || true,
+        lazy: () => {
+          // use classic script to avoid CORS issues
+          const script = document.createElement('script');
+          script.src = new URL(
+            '.rum/@adobe/helix-rum-enhancer@^1/src/index.js',
+            sampleRUM.baseURL,
+          ).href;
+          document.head.appendChild(script);
+          return true;
+        },
+      };
+      sendPing(data);
+      if (sampleRUM.cases[checkpoint]) {
+        sampleRUM.cases[checkpoint]();
       }
     }
-    if (window.hlx.rum && window.hlx.rum.isSelected && checkpoint) {
-      window.hlx.rum.collector(checkpoint, data, timeShift());
+    if (sampleRUM.always[checkpoint]) {
+      sampleRUM.always[checkpoint](data);
     }
-    document.dispatchEvent(new CustomEvent('rum', { detail: { checkpoint, data } }));
   } catch (error) {
     // something went wrong
   }
diff --git a/package-lock.json b/package-lock.json
index e493ea4..6e1a62e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@adobe/aem-lib",
-  "version": "1.5.2",
+  "version": "1.5.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@adobe/aem-lib",
-      "version": "1.5.2",
+      "version": "1.5.3",
       "license": "Apache License 2.0",
       "dependencies": {
         "@adobe/helix-rum-js": "1.8.0"
diff --git a/package.json b/package.json
index 71801fc..3721da7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@adobe/aem-lib",
-  "version": "1.5.2",
+  "version": "1.5.3",
   "description": "AEM Library",
   "type": "module",
   "scripts": {