diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..98cb55c
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2024-04-04 - Search performance optimization is missing in memory notes
+**Learning:** Found that `script.js` has not implemented `prepareSearchIndex` that is heavily discussed in the memory file. The filtering logic in `renderPDFs` evaluates `toLowerCase()` on multiple fields (title, description, category, author) dynamically during list rendering, missing the early returns and pre-indexed `_searchStr`.
+**Action:** Implementing `prepareSearchIndex` into `loadPDFDatabase` will improve list rendering significantly when large arrays are queried dynamically, reducing DOM re-renders and logic calculations dynamically.
diff --git a/script.js b/script.js
index 22f399d..86314be 100644
--- a/script.js
+++ b/script.js
@@ -338,6 +338,35 @@ function getAdData(slotName) {
 /* =========================================
    5. DATA LOADING WITH CACHING
    ========================================= */
+function prepareSearchIndex(pdfDatabase) {
+    const now = new Date();
+    pdfDatabase.forEach(pdf => {
+        // Handle Firebase Timestamp or standard Date string
+        let uploadDateObj;
+        if (pdf.uploadDate && typeof pdf.uploadDate.toDate === 'function') {
+            uploadDateObj = pdf.uploadDate.toDate();
+        } else if (pdf.uploadDate) {
+            uploadDateObj = new Date(pdf.uploadDate);
+        } else {
+            uploadDateObj = now;
+        }
+
+        // Cache derived properties
+        pdf._formattedDate = uploadDateObj.toLocaleDateString('en-US', {
+            year: 'numeric', month: 'short', day: 'numeric'
+        });
+
+        const timeDiff = now - uploadDateObj;
+        pdf._isNew = timeDiff < (7 * 24 * 60 * 60 * 1000);
+
+        const title = (pdf.title || '').toLowerCase();
+        const desc = (pdf.description || '').toLowerCase();
+        const cat = (pdf.category || '').toLowerCase();
+        const author = (pdf.author || '').toLowerCase();
+        pdf._searchStr = `${title} ${desc} ${cat} ${author}`;
+    });
+}
+
 function renderSemesterTabs() {
     const container = document.getElementById('semesterTabsContainer');
     if (!container) return;
@@ -454,6 +483,7 @@ async function loadPDFDatabase() {
 
         if (shouldUseCache) {
             pdfDatabase = cachedData;
+            prepareSearchIndex(pdfDatabase);
             // --- FIX: CALL THIS TO POPULATE UI ---
             syncClassSwitcher();
             renderSemesterTabs();
@@ -477,6 +507,8 @@ async function loadPDFDatabase() {
             data: pdfDatabase
         }));
 
+        prepareSearchIndex(pdfDatabase);
+
         // --- FIX: CALL THIS TO POPULATE UI ---
         syncClassSwitcher();
         renderPDFs();
@@ -905,26 +937,20 @@ function renderPDFs() {
 
     // Locate renderPDFs() in script.js and update the filter section
     const filteredPdfs = pdfDatabase.filter(pdf => {
-        const matchesSemester = pdf.semester === currentSemester;
-
-        // NEW: Check if the PDF class matches the UI's current class selection
-        // Note: If old documents don't have this field, they will be hidden.
-        const matchesClass = pdf.class === currentClass;
+        // Early returns for cheap equality checks
+        if (pdf.semester !== currentSemester) return false;
+        if (pdf.class !== currentClass) return false;
 
-        let matchesCategory = false;
         if (currentCategory === 'favorites') {
-            matchesCategory = favorites.includes(pdf.id);
-        } else {
-            matchesCategory = currentCategory === 'all' || pdf.category === currentCategory;
+            if (!favorites.includes(pdf.id)) return false;
+        } else if (currentCategory !== 'all') {
+            if (pdf.category !== currentCategory) return false;
         }
 
-        const matchesSearch = pdf.title.toLowerCase().includes(searchTerm) ||
-            pdf.description.toLowerCase().includes(searchTerm) ||
-            pdf.category.toLowerCase().includes(searchTerm) ||
-            pdf.author.toLowerCase().includes(searchTerm);
+        // Check pre-calculated search string
+        if (searchTerm && (!pdf._searchStr || !pdf._searchStr.includes(searchTerm))) return false;
 
-        // Update return statement to include matchesClass
-        return matchesSemester && matchesClass && matchesCategory && matchesSearch;
+        return true;
     });
 
     updatePDFCount(filteredPdfs.length);
@@ -994,9 +1020,7 @@ function createPDFCard(pdf, favoritesList, index = 0, highlightRegex = null) {
     const heartIconClass = isFav ? 'fas' : 'far';
     const btnActiveClass = isFav ? 'active' : '';
 
-    const uploadDateObj = new Date(pdf.uploadDate);
-    const timeDiff = new Date() - uploadDateObj;
-    const isNew = timeDiff < (7 * 24 * 60 * 60 * 1000); // 7 days
+    const isNew = pdf._isNew || false;
 
     const newBadgeHTML = isNew
         ? `<span style="background:var(--error-color); color:white; font-size:0.6rem; padding:2px 6px; border-radius:4px; margin-left:8px; vertical-align:middle;">NEW</span>`
@@ -1011,9 +1035,7 @@ function createPDFCard(pdf, favoritesList, index = 0, highlightRegex = null) {
     const categoryIcon = categoryIcons[pdf.category] || 'fa-file-pdf';
 
     // Formatting Date
-    const formattedDate = new Date(pdf.uploadDate).toLocaleDateString('en-US', {
-        year: 'numeric', month: 'short', day: 'numeric'
-    });
+    const formattedDate = pdf._formattedDate || '';
 
     // Uses global escapeHtml() now