diff --git a/lib/clouddrop-upload.js b/lib/clouddrop-upload.js
index 25a08de..5223b88 100644
--- a/lib/clouddrop-upload.js
+++ b/lib/clouddrop-upload.js
@@ -105,7 +105,7 @@ class ClouddropUploader {
     let bytesRead = 0;
     async function* generate() {
       yield preambleBuf;
-      const fileStream = fs.createReadStream(filePath, { highWaterMark: 256 * 1024 });
+      const fileStream = fs.createReadStream(filePath, { highWaterMark: 1024 * 1024 });
       for await (const chunk of fileStream) {
         if (signal && signal.aborted) throw new Error('Aborted');
         if (throttle) await throttle.consume(chunk.length, signal);
diff --git a/lib/config-store.js b/lib/config-store.js
index c455f35..9b81c8b 100644
--- a/lib/config-store.js
+++ b/lib/config-store.js
@@ -187,6 +187,7 @@ class ConfigStore {
     this._writeQueue = Promise.resolve(); // Serializes all writes to prevent race conditions
     this._cache = null;
     this._cacheKey = '';
+    this._perfLog = null;
 
     // Migrate config from old location if current doesn't exist
     if (!fs.existsSync(this.filePath) && app && app.isPackaged) {
@@ -228,7 +229,23 @@ class ConfigStore {
     catch { return JSON.parse(JSON.stringify(obj)); }
   }
 
+  setPerfLog(fn) { this._perfLog = typeof fn === 'function' ? fn : null; }
+
   load() {
+    if (!this._perfLog) return this._loadImpl();
+    const hadCache = !!this._cache;
+    const t0 = performance.now();
+    const r = this._loadImpl();
+    const dt = performance.now() - t0;
+    if (dt >= 20) {
+      const q = ((r && r.globalSettings && r.globalSettings.pendingQueue) || []).length;
+      const h = (r && r.history || []).length;
+      this._perfLog(`config-load wall=${dt.toFixed(0)}ms cache=${hadCache ? 'hit' : 'miss'} hist=${h} queue=${q}`);
+    }
+    return r;
+  }
+
+  _loadImpl() {
     try {
       // In-memory cache keyed on the file's mtime+size. The processed config
       // (merged + credential-decrypted) is reparsed/re-decrypted from disk ONLY
@@ -356,7 +373,16 @@ class ConfigStore {
   }
 
   _commit(config) {
-    return this._atomicWrite(this._serializeForDisk(config));
+    if (!this._perfLog) return this._atomicWrite(this._serializeForDisk(config));
+    const t0 = performance.now();
+    const data = this._serializeForDisk(config);
+    const dt = performance.now() - t0;
+    if (dt >= 20) {
+      const q = ((config.globalSettings && config.globalSettings.pendingQueue) || []).length;
+      const h = (config.history || []).length;
+      this._perfLog(`config-serialize wall=${dt.toFixed(0)}ms bytes=${data.length} hist=${h} queue=${q}`);
+    }
+    return this._atomicWrite(data);
   }
 
   _enqueueWrite(fn) {
diff --git a/lib/doodstream-upload.js b/lib/doodstream-upload.js
index 02fcaaa..1c3821b 100644
--- a/lib/doodstream-upload.js
+++ b/lib/doodstream-upload.js
@@ -339,7 +339,7 @@ class DoodstreamUploader {
     const epilogueBuf = Buffer.from(epilogue, 'utf-8');
     const totalSize = preambleBuf.length + fileSize + epilogueBuf.length;
 
-    const CHUNK_SIZE = 256 * 1024;
+    const CHUNK_SIZE = 1024 * 1024;
     let bytesRead = 0;
 
     async function* generate() {
diff --git a/lib/hosters.js b/lib/hosters.js
index 1069243..5bd7a5d 100644
--- a/lib/hosters.js
+++ b/lib/hosters.js
@@ -288,7 +288,7 @@ function createUploadBody(filePath, formFields, onProgress, throttle, signal) {
   const { boundary, preambleBuf, epilogueBuf, totalSize, fileSize } = buildMultipart(filePath, formFields);
 
   let bytesRead = 0;
-  const CHUNK_SIZE = 256 * 1024;
+  const CHUNK_SIZE = 1024 * 1024;
 
   async function* generate() {
     yield preambleBuf;
diff --git a/lib/vidmoly-upload.js b/lib/vidmoly-upload.js
index 608fcaf..cd9b145 100644
--- a/lib/vidmoly-upload.js
+++ b/lib/vidmoly-upload.js
@@ -187,7 +187,7 @@ class VidmolyUploader {
     const totalSize = preambleBuf.length + fileSize + epilogueBuf.length;
 
     let bytesRead = 0;
-    const CHUNK_SIZE = 256 * 1024;
+    const CHUNK_SIZE = 1024 * 1024;
 
     async function* generate() {
       yield preambleBuf;
diff --git a/lib/voe-upload.js b/lib/voe-upload.js
index 3f523d2..4c105c3 100644
--- a/lib/voe-upload.js
+++ b/lib/voe-upload.js
@@ -242,7 +242,7 @@ class VoeUploader {
     const totalSize = preambleBuf.length + fileSize + epilogueBuf.length;
 
     let bytesRead = 0;
-    const CHUNK_SIZE = 256 * 1024;
+    const CHUNK_SIZE = 1024 * 1024;
 
     async function* generate() {
       yield preambleBuf;
diff --git a/main.js b/main.js
index 4796004..b844a85 100644
--- a/main.js
+++ b/main.js
@@ -51,6 +51,7 @@ let _lastImportPath = null;
 let dropTargetWindow = null;
 let tray = null;
 const configStore = new ConfigStore(app);
+configStore.setPerfLog((m) => { try { logInfo(m); } catch {} });
 let uploadManager = null;
 let diagnosticAgent = null;
 let _diagHandler = null;
diff --git a/package.json b/package.json
index c092181..efe1356 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "multi-hoster-uploader",
-  "version": "3.3.97",
+  "version": "3.3.98",
   "description": "Upload files to doodstream, voe, vidmoly, byse simultaneously",
   "main": "main.js",
   "scripts": {
diff --git a/tasks/lessons.md b/tasks/lessons.md
index bdb77ed..ac82809 100644
--- a/tasks/lessons.md
+++ b/tasks/lessons.md
@@ -1,5 +1,33 @@
 # Lessons
 
+## 2026-06-21 — Ein-Variablen-Disziplin: nicht zwei Fixes bündeln, wenn einer den anderen maskiert
+**Symptom:** Nach dem tp=8-Win wollte ich in EINEM Build A (1MB highWaterMark, Read-Burst) + B (Renderer
+chunked rAF Batch-Drain, der 243ms-Longtask) + C-Instrument shippen.
+**Root cause / Korrektur (Advisor):** Der Renderer war 14/15 Fenstern gesund; der EINE 243ms-Longtask (W14)
+ist laut beiden Agenten DOWNSTREAM des Main-Thread-Read-Bursts (geflutetes IPC). Fix A reduziert diese
+Stalls → der Renderer-Longtask verschwindet wahrscheinlich OHNE B. B mitzuliefern (a) verwässert die nächste
+Messung (war die Besserung A oder B?) und (b) fasst den Progress-Hot-Path an, der hier schon gebissen hat
+(formatDateTime-Burst, ghost-fix).
+**Regel:** Wenn Fix A einen vermuteten Symptom-Treiber X reduziert und Fix B genau X behandeln würde —
+NUR A shippen, messen, B nur nachziehen wenn X überlebt. Sonst kann das nächste Log nicht sauber attribuieren.
+Bei gekoppelten Symptomen ist die Reihenfolge (Upstream-Fix zuerst, dann messen) wichtiger als „alles auf
+einmal".
+**Wie anwenden:** Vor dem Bündeln fragen: „Maskiert Fix A die Wirkung, die Fix B beheben soll?" Wenn ja →
+entkoppeln, A zuerst, eine Variable pro Build.
+
+## 2026-06-21 — Nicht aus EINEM konfundierten Sample eine Ursache behaupten
+**Symptom:** Ich wollte dem User sagen „1-Sekunden-Persist-Freeze gefunden" auf Basis von W13 (max=1021ms,
+heap→142MB).
+**Root cause / Korrektur (Advisor):** W13 ist EIN Sample und konfundiert (hat gleichzeitig FSReqCallback=66)
+und das EINZIGE Heap-Spike-Fenster. Die anderen isolierten Maxes (W4 415ms/heap41, W10 852ms/heap18) haben
+NIEDRIGEN Heap → sind KEIN 140MB-structuredClone+stringify → eine andere Ursache (account-failed sync load()
+nahe Connection-Churn). Eine Behauptung aus einem konfundierten Punkt hätte den falschen Fix priorisiert.
+**Regel:** Bei isolierten Spitzen erst die Co-Signale (heap, FSReq, gc, Nachbarfenster) gegenchecken, ob sie
+EINE Familie sind. Wenn die Magnitude-Signatur (hier: Heap-Spike) nicht bei allen passt → es sind mehrere
+Ursachen. „Instrumentieren + bestätigen", nicht „gefunden", solange nur ein konfundierter Punkt existiert.
+**Wie anwenden:** Vor „Ursache X gefunden": gibt es ≥2 unkonfundierte Samples mit derselben Signatur? Wenn
+nein → als Hypothese formulieren und messen, nicht als Befund verkaufen.
+
 ## 2026-06-21 — Histogram-Korrelation beweist KEINE Kausalrichtung; rss-Mathe als Sanity-Check
 **Symptom:** ELD-Spikes korrelierten exakt mit hohem `FSReqCallback` (File-Reads in flight) → ich wollte
 sofort ein Read-Concurrency-Semaphore über 5 Dateien bauen.
diff --git a/tasks/todo.md b/tasks/todo.md
index a492c75..de67d9d 100644
--- a/tasks/todo.md
+++ b/tasks/todo.md
@@ -1,3 +1,46 @@
+# v3.3.98 — read-burst absorption (1MB hwm) + persist/load instrument; B (renderer) DEFERRED
+
+v3.3.97 (threadpool 64→8) was a DECISIVE win: mean ELD 200ms→~11ms at 70 active (18×), renderer healthy
+14/15 windows. User: "ganz flüssig isses noch nicht". A 5-agent ultracode workflow + adversarial verify
+localized the RESIDUAL to TWO distinct, measured spike sources (full data: subagents output wjskjo1xk):
+
+1. READ-BURSTS (tail W13/14/15, 15:18:53-19:04): FSReqCallback 66/70/46 vs threadpool=8 (~8.75× queue
+   depth), SimpleWriteWrap collapses to 7/4/24, mean climbs 12.9→30.3→41.9ms. GC EXCLUDED (gcMax ≤27ms
+   always). The FSReq↔SimpleWrite inversion at stable active=70/pending=1287 proves reads are CAUSAL, not
+   a symptom of a block elsewhere.
+2. SYNC CONFIG PERSIST (suspected): save()→load() reparses the WHOLE electron-config.json (1287-job
+   pendingQueue nested in globalSettings + full history) on every persist because _atomicWrite nulls the
+   cache; _serializeForDisk JSON.stringify(...,null,2) of all of it. W13's single 1021ms max with heap→142MB
+   fits a big synchronous structuredClone+stringify. CAVEAT (advisor): W13 is ONE confounded sample (also
+   FSReq=66) and the ONLY heap-spike window; W4(415ms,heap41) & W10(852ms,heap18) are LOW-heap → NOT persist
+   clones → likely the SECONDARY suspect: account-failed's synchronous configStore.load() per failure near
+   connection churn (W6 teardown had doodstream connect-timeouts). So: INSTRUMENT, don't claim "found a 1s
+   freeze".
+
+SHIPPED v3.3.98 (one-variable discipline — advisor cut B to keep the next measurement clean):
+- A: highWaterMark 256KB→1MB in all 5 streaming read loops (hosters.js:291, doodstream:342, voe:245,
+  vidmoly:190 CHUNK_SIZE consts; clouddrop:108 inline — NOT clouddrop:12's 16MB server chunk). Keep tp=8.
+  Deepens per-stream read-ahead 0.43s→~1.7s (absorbs threadpool-queue latency so writes don't starve),
+  4× fewer read completions + allocs. Zero multipart byte-risk (Content-Length=preamble+fileSize+epilogue,
+  independent of chunk size). REVERSIBLE PROBE; read-semaphore held in reserve (trigger: FSReq still ~70 +
+  writes starved + mean elevated after 1MB).
+- C-instrument (BROADENED per advisor): config-store.js times load() (full reparse, incl. account-failed
+  path) AND _commit serialize; logs `config-load wall=Xms cache=hit/miss hist=N queue=M` and
+  `config-serialize wall=Xms bytes=Y hist=N queue=M` when ≥20ms (perfLog hook set in main.js via
+  configStore.setPerfLog→logInfo). load() split into wrapper + _loadImpl. 397 tests pass.
+- B (renderer chunked rAF batch drain, app.js:188-193 — the 243ms longtask at W14) DEFERRED: renderer was
+  healthy 14/15 windows and the one longtask is DOWNSTREAM of the main-thread read-burst flooding IPC.
+  Fix A should make it self-heal. Bundling B would confound attribution + touches the progress hot path
+  that bit before (formatDateTime burst, ghost-fix). Add B next round ONLY if renderer still janks after A.
+
+NEXT LOG answers 3 things cleanly: (1) did A kill the read-bursts (FSReq per-window + tail mean drop)?
+(2) is the persist/load actually heavy (new config-load/config-serialize lines + their wall/queue/hist)?
+(3) did the renderer self-heal from A alone (longtasks back to 0)? Then decide: persist refactor for v3.3.99
+(queue-out-of-config OR cache-repopulation — latter lower-risk but renderer's incoming globalSettings isn't
+default-merged like load() produces, so confirm merge-equivalence first), and/or B, and/or read-semaphore.
+
+---
+
 # v3.3.97 — DECISIVE ELD finding: file-read phase-flip + threadpool 64→8 + GC instrument
 
 The v3.3.96 `eventloop-delay` logs gave the decisive signal. At CONSTANT active-count, the system flips