diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..9c15082
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,4 @@
+
+## 2024-04-13 - [Pre-calculating derived search strings and date formatting]
+**Learning:** High-frequency loop performance in lists like `renderPDFs` can degrade severely when performing string concatenations (`pdf.title + pdf.description + ...`), `toLowerCase()` conversions, or `Intl.DateTimeFormat` evaluations dynamically for every item during every render.
+**Action:** Always pre-calculate these derived properties (e.g., `_searchStr`, `_formattedDate`, `_isNew`) iteratively immediately after the data completes loading, keeping the render loop extremely lightweight and purely responsible for DOM updates.
diff --git a/script.js b/script.js
index 22f399d..b3611be 100644
--- a/script.js
+++ b/script.js
@@ -416,6 +416,34 @@ async function syncClassSwitcher() {
     renderSemesterTabs();
 }
 
+function prepareSearchIndex(data) {
+    const now = Date.now();
+    const sevenDays = 7 * 24 * 60 * 60 * 1000;
+    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 desc = pdf.description || '';
+        const cat = pdf.category || '';
+        const author = pdf.author || '';
+        pdf._searchStr = `${title} ${desc} ${cat} ${author}`.toLowerCase();
+
+        // Pre-calculate date properties
+        const uploadDateObj = new Date(pdf.uploadDate);
+        if (!isNaN(uploadDateObj.getTime())) {
+            const timeDiff = now - uploadDateObj.getTime();
+            pdf._isNew = timeDiff < sevenDays;
+            pdf._formattedDate = dateFormatter.format(uploadDateObj);
+        } else {
+            pdf._isNew = false;
+            pdf._formattedDate = "Unknown Date";
+        }
+    });
+}
+
 async function loadPDFDatabase() {
     if (isMaintenanceActive) return;
 
@@ -454,6 +482,7 @@ async function loadPDFDatabase() {
 
         if (shouldUseCache) {
             pdfDatabase = cachedData;
+            prepareSearchIndex(pdfDatabase);
             // --- FIX: CALL THIS TO POPULATE UI ---
             syncClassSwitcher();
             renderSemesterTabs();
@@ -477,6 +506,8 @@ async function loadPDFDatabase() {
             data: pdfDatabase
         }));
 
+        prepareSearchIndex(pdfDatabase);
+
         // --- FIX: CALL THIS TO POPULATE UI ---
         syncClassSwitcher();
         renderPDFs();
@@ -918,10 +949,7 @@ function renderPDFs() {
             matchesCategory = currentCategory === 'all' || pdf.category === currentCategory;
         }
 
-        const matchesSearch = pdf.title.toLowerCase().includes(searchTerm) ||
-            pdf.description.toLowerCase().includes(searchTerm) ||
-            pdf.category.toLowerCase().includes(searchTerm) ||
-            pdf.author.toLowerCase().includes(searchTerm);
+        const matchesSearch = pdf._searchStr ? pdf._searchStr.includes(searchTerm) : false;
 
         // Update return statement to include matchesClass
         return matchesSemester && matchesClass && matchesCategory && matchesSearch;
@@ -994,9 +1022,7 @@ 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>`
@@ -1011,7 +1037,7 @@ 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', {
+    const formattedDate = pdf._formattedDate || new Date(pdf.uploadDate).toLocaleDateString('en-US', {
         year: 'numeric', month: 'short', day: 'numeric'
     });