diff --git a/package.json b/package.json
index fa4f021..384b86a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "multi-hoster-uploader",
-  "version": "3.3.99",
+  "version": "3.3.100",
   "description": "Upload files to doodstream, voe, vidmoly, byse simultaneously",
   "main": "main.js",
   "scripts": {
diff --git a/renderer/app.js b/renderer/app.js
index 9b469db..bbba33b 100644
--- a/renderer/app.js
+++ b/renderer/app.js
@@ -20,13 +20,38 @@ let uploading = false;
 let healthCheckRunning = false;
 
 let _rLongTasks = 0, _rLongTaskMax = 0, _rFrameLast = 0, _rFrameWorst = 0, _rFrameCount = 0, _rFrameJank = 0, _rPerfLastLog = 0, _rPerfWindowStart = 0;
+function _rElLabel(el) {
+  try {
+    if (!el || !el.tagName) return '?';
+    let s = el.tagName.toLowerCase();
+    if (el.id) s += '#' + el.id;
+    else if (el.className && typeof el.className === 'string') { const c = el.className.trim().split(/\s+/)[0]; if (c) s += '.' + c; }
+    const a = el.getAttribute && (el.getAttribute('data-action') || el.getAttribute('data-tab') || el.getAttribute('aria-label') || el.getAttribute('title'));
+    if (a) s += `[${String(a).slice(0, 24)}]`;
+    return s;
+  } catch { return '?'; }
+}
 try {
   if (window.PerformanceObserver) {
     new window.PerformanceObserver((list) => {
-      for (const e of list.getEntries()) { _rLongTasks++; if (e.duration > _rLongTaskMax) _rLongTaskMax = e.duration; }
+      for (const e of list.getEntries()) {
+        _rLongTasks++;
+        if (e.duration > _rLongTaskMax) _rLongTaskMax = e.duration;
+        if (e.duration >= 100 && window.api && window.api.debugLog) window.api.debugLog(`renderer-longtask dur=${Math.round(e.duration)}ms`);
+      }
     }).observe({ entryTypes: ['longtask'] });
   }
 } catch {}
+try {
+  if (window.PerformanceObserver) {
+    new window.PerformanceObserver((list) => {
+      for (const e of list.getEntries()) {
+        const proc = Math.round((e.processingEnd || 0) - (e.processingStart || 0));
+        if (window.api && window.api.debugLog) window.api.debugLog(`renderer-interaction ${e.name} dur=${Math.round(e.duration)}ms proc=${proc}ms target=${_rElLabel(e.target)}`);
+      }
+    }).observe({ type: 'event', durationThreshold: 50, buffered: true });
+  }
+} catch {}
 function _rFrameTick(ts) {
   if (_rFrameLast) { const d = ts - _rFrameLast; _rFrameCount++; if (d > _rFrameWorst) _rFrameWorst = d; if (d > 33) _rFrameJank++; }
   _rFrameLast = ts;
diff --git a/tasks/todo.md b/tasks/todo.md
index 8e85c7c..b47bce3 100644
--- a/tasks/todo.md
+++ b/tasks/todo.md
@@ -1,3 +1,19 @@
+# v3.3.100 — close the LAST measurement gap: renderer interaction timing (switches/clicks)
+
+User asked "haben wir wirklich ALLES gemessen, auch switches/wechsel?". Audit: main-side was already
+fully covered (IPC wrapper ≥50ms on every handler, main-longtask >100ms with lastIpc, config instrument);
+account switchAccount is a trivial sync Map-set + the rotation work is async (can't block) → already covered.
+The REAL gap was RENDERER-side: renderer-perf was upload-gated (idle clicks unmeasured) and only aggregate
+(no per-interaction latency, no element attribution). Closed it (renderer/app.js, additive, self-silencing):
+- Event Timing API observer (`type:'event', durationThreshold:50, buffered`) → `renderer-interaction <type>
+  dur=Xms proc=Yms target=<el>` for EVERY UI interaction ≥50ms (switch/sort-header/tab/button), always-on,
+  names the element (id/class/data-action/aria-label). The direct "click→reaction" latency.
+- Idle renderer-longtask logging: any longtask ≥100ms logged immediately (`renderer-longtask dur=Xms`),
+  not just during uploads.
+405 tests pass, clean boot. Now EVERY action — main or renderer, idle or under load — names itself if slow.
+
+---
+
 # v3.3.99 — THE KILL: 38.5MB config-thrash → history split out of the hot config + full instrumentation
 
 THE ROOT CAUSE (from v3.3.98's instrument, the real "bread"): electron-config.json was **38.5MB** and got