diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..8ce14b1
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,2 @@
+## 2024-05-24 - Pre-calculating derived properties
+**Learning:** The memory mentions that pre-calculating _searchStr, _isNew, _formattedDate speeds things up 128x (115ms to 0.9ms).
diff --git a/script.js b/script.js
index 22f399d..1cd6f44 100644
--- a/script.js
+++ b/script.js
@@ -454,6 +454,7 @@ async function loadPDFDatabase() {
 
         if (shouldUseCache) {
             pdfDatabase = cachedData;
+            prepareSearchIndex(pdfDatabase);
             // --- FIX: CALL THIS TO POPULATE UI ---
             syncClassSwitcher();
             renderSemesterTabs();
@@ -477,6 +478,8 @@ async function loadPDFDatabase() {
             data: pdfDatabase
         }));
 
+        prepareSearchIndex(pdfDatabase);
+
         // --- FIX: CALL THIS TO POPULATE UI ---
         syncClassSwitcher();
         renderPDFs();
@@ -503,6 +506,40 @@ function hidePreloader() {
     }
 }
 
+/* =========================================
+   5.5 PERFORMANCE INDEXING
+   ========================================= */
+function prepareSearchIndex(data) {
+    const now = new Date();
+    // Cache the formatter for maximum performance
+    const dateFormatter = new Intl.DateTimeFormat('en-US', {
+        year: 'numeric', month: 'short', day: 'numeric'
+    });
+
+    data.forEach(pdf => {
+        // Pre-calculate search string
+        const title = pdf.title || '';
+        const description = pdf.description || '';
+        const category = pdf.category || '';
+        const author = pdf.author || '';
+        pdf._searchStr = `${title} ${description} ${category} ${author}`.toLowerCase();
+
+        // Handle both Firestore Timestamp (.toDate) and string dates
+        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; // Fallback
+        }
+
+        // Pre-calculate expensive date logic
+        pdf._isNew = (now - uploadDateObj) < (7 * 24 * 60 * 60 * 1000);
+        pdf._formattedDate = dateFormatter.format(uploadDateObj);
+    });
+}
+
 /* =========================================
    6. MAINTENANCE & HOLIDAYS
    ========================================= */
@@ -905,26 +942,23 @@ function renderPDFs() {
 
     // Locate renderPDFs() in script.js and update the filter section
     const filteredPdfs = pdfDatabase.filter(pdf => {
-        const matchesSemester = pdf.semester === currentSemester;
+        if (pdf.semester !== currentSemester) return false;
 
         // 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;
+        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);
+        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 +1028,7 @@ 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;
 
     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 +1043,7 @@ 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