perf: lazy history refresh + append-only recent panel + queue-cleanup merge

Three more targeted wins:

  - loadHistory() was called unconditionally on every handleBatchDone,
    doing an IPC roundtrip + full history-table rebuild even when the
    user is on the Upload tab and can't see it. Now it sets a dirty
    flag and the actual refresh is deferred until the user switches
    to the Verlauf tab. On a fresh tab click it always runs.

  - renderRecentUploadsPanel append-only fast path: when the sort is
    'date desc' (the default) and the dataset only grew, the panel
    inserts the new rows at the top via insertAdjacentHTML instead
    of rebuilding the 5000-row tbody from scratch. Length shrinks or
    sort-change still trigger a full rebuild.

  - handleBatchDone's removeFromQueueOnDone cleanup now does one pass
    (build keep-list + detach from index together) instead of two
    separate filter() scans over queueJobs.

renderer/app.js

@@ -200,13 +200,21 @@ async function init() {
 }
 
 // --- Tab switching ---
+let _historyDirty = false;
+function _isHistoryTabActive() {
+  const tab = document.querySelector('.tab.active');
+  return !!(tab && tab.dataset.view === 'history');
+}
 document.querySelectorAll('.tab').forEach(tab => {
   tab.addEventListener('click', () => {
     document.querySelectorAll('.tab').forEach(t => t.classList.remove('active'));
     document.querySelectorAll('.view').forEach(v => v.classList.remove('active'));
     tab.classList.add('active');
     document.getElementById(`${tab.dataset.view}-view`).classList.add('active');
-    if (tab.dataset.view === 'history') loadHistory();
+    if (tab.dataset.view === 'history') {
+      _historyDirty = false;
+      loadHistory();
+    }
   });
 });
 
@@ -1820,16 +1828,25 @@ function handleBatchDone(summary) {
   updateQueueActionButtons();
   renderQueueTable();
   renderRecentUploadsPanel();
-  loadHistory();
+  // History is only visible on the Verlauf tab. Mark it dirty and refresh when
+  // the user actually switches to it — skips an IPC + full table rebuild per
+  // batch-done when the user is watching the upload view.
+  _historyDirty = true;
+  if (_isHistoryTabActive()) loadHistory();
 
   const removeOnDone = config.globalSettings && config.globalSettings.removeFromQueueOnDone;
   if (removeOnDone) {
-    const doneJobs = queueJobs.filter(j => j.status === 'done');
-    for (const job of doneJobs) {
+    // Single pass: build the keep-list and clean up the index for removed jobs.
+    const nextJobs = [];
+    for (const job of queueJobs) {
+      if (job.status === 'done') {
         removeJobFromIndex(job);
         selectedJobIds.delete(job.id);
+      } else {
+        nextJobs.push(job);
       }
-    queueJobs = queueJobs.filter(j => j.status !== 'done');
+    }
+    queueJobs = nextJobs;
     renderQueueTable();
   }
 
@@ -3215,24 +3232,50 @@ function updateRecentSortHeaders() {
 
 let _recentListenersBound = false;
 
+function _buildRecentRowHtml(row) {
+  const cls = `recent-file-row${row.isError ? ' error' : ''}${selectedRecentIds.has(row.order) ? ' selected' : ''}`;
+  return `<tr class="${cls}" data-order="${row.order}" data-link="${escapeAttr(row.link)}">`
+    + `<td>${escapeHtml(row.date)}</td>`
+    + `<td title="${escapeAttr(row.filename)}">${escapeHtml(row.filename)}</td>`
+    + `<td>${escapeHtml(row.host)}</td>`
+    + `<td title="${escapeAttr(row.link)}">${escapeHtml(row.link)}</td>`
+    + `</tr>`;
+}
+
+// Tracks the last rendered dataset so we can append-only when the user is just
+// accumulating new uploads (the default case: sort=date desc, rows only grow).
+let _recentLastRenderedSig = '';
+let _recentLastRenderedLen = 0;
+
 function renderRecentUploadsPanel() {
   const tbody = document.getElementById('recentFilesBody');
   if (!tbody) return;
   if (!sessionFilesData.length) {
     tbody.innerHTML = '<tr><td colspan="4" class="empty-state">Noch keine Uploads in dieser Session.</td></tr>';
+    _recentLastRenderedSig = '';
+    _recentLastRenderedLen = 0;
     return;
   }
 
   const rows = sortRecentFiles(sessionFilesData);
+  const sig = `${recentSortState.key}|${recentSortState.direction}`;
+  const dateDescAppendOnly = sig === 'date|desc'
+    && _recentLastRenderedSig === sig
+    && rows.length > _recentLastRenderedLen
+    && tbody.querySelectorAll('.recent-file-row').length === _recentLastRenderedLen;
 
-  tbody.innerHTML = rows.map(row => `
-    <tr class="recent-file-row${row.isError ? ' error' : ''}${selectedRecentIds.has(row.order) ? ' selected' : ''}" data-order="${row.order}" data-link="${escapeAttr(row.link)}">
-      <td>${escapeHtml(row.date)}</td>
-      <td title="${escapeAttr(row.filename)}">${escapeHtml(row.filename)}</td>
-      <td>${escapeHtml(row.host)}</td>
-      <td title="${escapeAttr(row.link)}">${escapeHtml(row.link)}</td>
-    </tr>
-  `).join('');
+  if (dateDescAppendOnly) {
+    // Fast path: only new rows (date desc puts newest on top) — insert them
+    // at the top without rebuilding the 5000-row tbody below.
+    const added = rows.length - _recentLastRenderedLen;
+    let html = '';
+    for (let i = 0; i < added; i++) html += _buildRecentRowHtml(rows[i]);
+    tbody.insertAdjacentHTML('afterbegin', html);
+  } else {
+    tbody.innerHTML = rows.map(_buildRecentRowHtml).join('');
+  }
+  _recentLastRenderedSig = sig;
+  _recentLastRenderedLen = rows.length;
 
   // Event delegation – bind once, not per-row
   if (!_recentListenersBound) {