diff --git a/src/app/api/notes/route.ts b/src/app/api/notes/route.ts
index 8627563..182e6a0 100644
--- a/src/app/api/notes/route.ts
+++ b/src/app/api/notes/route.ts
@@ -27,7 +27,7 @@ export async function GET(req: NextRequest) {
     const shortcut = sp.get('shortcut') === 'true';
     const sortBy = sp.get('sortBy') || 'updatedAt';
     const sortDir = (sp.get('sortDir') === 'asc' ? 'asc' : 'desc') as 'asc' | 'desc';
-    const limit = Math.min(parseInt(sp.get('limit') || '500', 10) || 500, 2000);
+    const limit = Math.min(parseInt(sp.get('limit') || '50', 10) || 50, 150);
     const offset = parseInt(sp.get('offset') || '0', 10) || 0;
 
     const where = buildNoteWhereClause({
diff --git a/src/components/EvercloneWorkspace.tsx b/src/components/EvercloneWorkspace.tsx
index 112c84e..fd10c15 100644
--- a/src/components/EvercloneWorkspace.tsx
+++ b/src/components/EvercloneWorkspace.tsx
@@ -65,6 +65,9 @@ import NoteHistoryModal from './NoteHistoryModal';
 import KeyboardShortcutsModal from './KeyboardShortcutsModal';
 import { PdfAutoThumbnail, InlinePdfViewerCard } from './PdfNoteComponents';
 
+// Maximum notes loaded per page/batch to ensure low memory usage and fast render times
+const NOTES_PAGE_SIZE = 40;
+
 export default function EvercloneWorkspace() {
   const [sidebar, setSidebar] = useState<SidebarData>({
     stacks: [],
@@ -344,7 +347,7 @@ export default function EvercloneWorkspace() {
   }, []);
 
   const buildNoteQueryParams = useCallback(
-    (offset = 0, limit = 150) => {
+    (offset = 0, limit = NOTES_PAGE_SIZE) => {
       const sp = new URLSearchParams();
       if (debouncedSearch.trim()) sp.set('q', debouncedSearch.trim());
       if (activeView === 'notebook' && selectedNotebookId) {
@@ -404,7 +407,7 @@ export default function EvercloneWorkspace() {
       const currentReqId = ++listRequestIdRef.current;
       setLoadingList(true);
       try {
-        const sp = buildNoteQueryParams(0, 150);
+        const sp = buildNoteQueryParams(0, NOTES_PAGE_SIZE);
         const res = await fetch(`/api/notes?${sp.toString()}`);
         if (!res.ok) return;
         const data = await res.json();
@@ -442,7 +445,7 @@ export default function EvercloneWorkspace() {
     const currentReqId = listRequestIdRef.current;
     setLoadingMore(true);
     try {
-      const sp = buildNoteQueryParams(notes.length, 150);
+      const sp = buildNoteQueryParams(notes.length, NOTES_PAGE_SIZE);
       const res = await fetch(`/api/notes?${sp.toString()}`);
       if (!res.ok) return;
       const data = await res.json();
@@ -2820,6 +2823,8 @@ export default function EvercloneWorkspace() {
                               <img
                                 src={effectiveThumbUrl}
                                 alt=""
+                                loading="lazy"
+                                decoding="async"
                                 className="w-full h-full object-cover group-hover/card:scale-105 transition duration-300"
                               />
                               {firstPdf && (
@@ -3082,6 +3087,8 @@ export default function EvercloneWorkspace() {
                             <img
                               src={effectiveThumbUrl}
                               alt=""
+                              loading="lazy"
+                              decoding="async"
                               className="w-14 h-14 object-cover rounded-lg border border-gray-200 bg-white"
                             />
                             {firstPdf && (
diff --git a/src/components/PdfNoteComponents.tsx b/src/components/PdfNoteComponents.tsx
index 6b986cc..56fa60c 100644
--- a/src/components/PdfNoteComponents.tsx
+++ b/src/components/PdfNoteComponents.tsx
@@ -69,6 +69,8 @@ export function PdfAutoThumbnail({
             <img
               src={dataUrl}
               alt="PDF Page 1"
+              loading="lazy"
+              decoding="async"
               className="w-full h-full object-cover object-top group-hover/card:scale-105 transition duration-300"
             />
             <span className="absolute bottom-1.5 left-2 px-1.5 py-0.5 rounded bg-red-600/90 text-white text-[9px] font-bold uppercase tracking-wider shadow">
@@ -103,6 +105,8 @@ export function PdfAutoThumbnail({
           <img
             src={dataUrl}
             alt="PDF Page 1"
+            loading="lazy"
+            decoding="async"
             className="w-full h-full object-cover object-top bg-white"
           />
           <span className="absolute bottom-0.5 right-0.5 px-1 py-0.1 rounded bg-red-600/90 text-white text-[8px] font-bold uppercase">
diff --git a/src/lib/pdfClient.ts b/src/lib/pdfClient.ts
index ab2d104..401a86f 100644
--- a/src/lib/pdfClient.ts
+++ b/src/lib/pdfClient.ts
@@ -52,24 +52,55 @@ export function loadPdfJs(): Promise<any> {
 }
 
 const pageRenderCache = new Map<string, string>();
+const MAX_CACHE_SIZE = 40;
+
+// Concurrency queue to throttle client-side PDF rendering (max 1 active worker render at a time)
+let activeRenders = 0;
+const renderQueue: Array<() => void> = [];
+
+async function acquireRenderSlot(): Promise<() => void> {
+  if (activeRenders < 1) {
+    activeRenders++;
+    return () => releaseRenderSlot();
+  }
+  return new Promise((resolve) => {
+    renderQueue.push(() => {
+      activeRenders++;
+      resolve(() => releaseRenderSlot());
+    });
+  });
+}
+
+function releaseRenderSlot(): void {
+  activeRenders--;
+  if (renderQueue.length > 0) {
+    const next = renderQueue.shift();
+    next?.();
+  }
+}
 
 /**
  * Renders a single page of a PDF (default Page 1) into a crisp JPEG data URL.
+ * Throttled to 1 concurrent render with automatic PDF.js memory destruction.
  */
 export async function renderPdfPageToDataUrl(
   pdfUrl: string,
   pageNumber = 1,
-  targetSize = 480
+  targetSize = 360
 ): Promise<string | null> {
   const cacheKey = `${pdfUrl}#page=${pageNumber}@${targetSize}`;
   if (pageRenderCache.has(cacheKey)) {
     return pageRenderCache.get(cacheKey)!;
   }
 
+  const release = await acquireRenderSlot();
+  let loadingTask: any = null;
+  let pdf: any = null;
+
   try {
     const pdfjsLib = await loadPdfJs();
-    const loadingTask = pdfjsLib.getDocument(pdfUrl);
-    const pdf = await loadingTask.promise;
+    loadingTask = pdfjsLib.getDocument(pdfUrl);
+    pdf = await loadingTask.promise;
 
     if (pageNumber < 1 || pageNumber > pdf.numPages) {
       return null;
@@ -94,12 +125,30 @@ export async function renderPdfPageToDataUrl(
 
     await page.render({ canvasContext: ctx, viewport }).promise;
 
-    const dataUrl = canvas.toDataURL('image/jpeg', 0.86);
+    const dataUrl = canvas.toDataURL('image/jpeg', 0.78);
+
+    // Evict oldest if cache exceeds limit
+    if (pageRenderCache.size >= MAX_CACHE_SIZE) {
+      const oldestKey = pageRenderCache.keys().next().value;
+      if (oldestKey) pageRenderCache.delete(oldestKey);
+    }
     pageRenderCache.set(cacheKey, dataUrl);
+
+    // Explicitly release canvas memory
+    canvas.width = 0;
+    canvas.height = 0;
+
     return dataUrl;
   } catch (err) {
     console.warn('PDF thumbnail render error:', err);
     return null;
+  } finally {
+    try {
+      if (pdf?.cleanup) pdf.cleanup();
+      if (pdf?.destroy) await pdf.destroy();
+      if (loadingTask?.destroy) await loadingTask.destroy();
+    } catch {}
+    release();
   }
 }