diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..e71483e
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2024-04-14 - Pre-calculate derived search fields for filter loops
+**Learning:** High-frequency render/filter loops can be severely bottlenecked by inline string and date manipulation functions (like `.toLowerCase()` and `new Date().toLocaleDateString()`).
+**Action:** Always pre-calculate and index derived properties (like search strings and formatted dates) immediately after data load and attach them to the objects, reducing the cost of per-render calculations and significantly improving list rendering/filtering performance.
diff --git a/script.js b/script.js
index 22f399d..e236fee 100644
--- a/script.js
+++ b/script.js
@@ -416,6 +416,32 @@ async function syncClassSwitcher() {
     renderSemesterTabs();
 }
 
+
+// ⚡ Bolt: Pre-calculates derived properties to avoid expensive per-render calculations
+function prepareSearchIndex(pdfs) {
+    const dateFormatter = new Intl.DateTimeFormat("en-US", {
+        year: "numeric", month: "short", day: "numeric"
+    });
+    const now = new Date();
+    const SEVEN_DAYS = 7 * 24 * 60 * 60 * 1000;
+
+    pdfs.forEach(pdf => {
+        if (!pdf._searchStr) {
+            pdf._searchStr = `${pdf.title} ${pdf.description} ${pdf.category} ${pdf.author}`.toLowerCase();
+        }
+        if (!pdf._formattedDate) {
+            const uploadDate = new Date(pdf.uploadDate);
+            if (!isNaN(uploadDate)) {
+                pdf._formattedDate = dateFormatter.format(uploadDate);
+                pdf._isNew = (now - uploadDate) < SEVEN_DAYS;
+            } else {
+                pdf._formattedDate = "Unknown Date";
+                pdf._isNew = false;
+            }
+        }
+    });
+}
+
 async function loadPDFDatabase() {
     if (isMaintenanceActive) return;
 
@@ -454,6 +480,7 @@ async function loadPDFDatabase() {
 
         if (shouldUseCache) {
             pdfDatabase = cachedData;
+            prepareSearchIndex(pdfDatabase);
             // --- FIX: CALL THIS TO POPULATE UI ---
             syncClassSwitcher();
             renderSemesterTabs();
@@ -477,6 +504,7 @@ async function loadPDFDatabase() {
             data: pdfDatabase
         }));
 
+        prepareSearchIndex(pdfDatabase);
         // --- FIX: CALL THIS TO POPULATE UI ---
         syncClassSwitcher();
         renderPDFs();
@@ -905,26 +933,23 @@ 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);
+            if (!favorites.includes(pdf.id)) return false;
         } else {
-            matchesCategory = currentCategory === 'all' || pdf.category === currentCategory;
+            if (currentCategory !== 'all' && 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) {
+            if (!pdf._searchStr.includes(searchTerm)) return false;
+        }
 
-        // Update return statement to include matchesClass
-        return matchesSemester && matchesClass && matchesCategory && matchesSearch;
+        return true;
     });
 
     updatePDFCount(filteredPdfs.length);
@@ -994,9 +1019,7 @@ 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 +1034,7 @@ 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 || 'Unknown Date';
 
     // Uses global escapeHtml() now