diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..627d148
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2024-05-19 - Adding _searchStr derived field
+**Learning:** We need to add `_searchStr` for performance so `renderPDFs` doesn't do multiple `toLowerCase` conversions for each record per keystroke.
+**Action:** Add `prepareSearchIndex` and calculate runtime derived fields.
diff --git a/script.js b/script.js
index 22f399d..553d7e6 100644
--- a/script.js
+++ b/script.js
@@ -385,6 +385,35 @@ window.changeSemester = function (sem) {
     renderPDFs();
 };
 
+function prepareSearchIndex(pdfs) {
+    const now = new Date();
+    pdfs.forEach(pdf => {
+        const titleStr = typeof pdf.title === 'string' ? pdf.title : '';
+        const descStr = typeof pdf.description === 'string' ? pdf.description : '';
+        const catStr = typeof pdf.category === 'string' ? pdf.category : '';
+        const authorStr = typeof pdf.author === 'string' ? pdf.author : '';
+
+        // Add pre-calculated derived fields for faster searching
+        pdf._searchStr = `${titleStr} ${descStr} ${catStr} ${authorStr}`.toLowerCase();
+
+        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 = new Date(0);
+        }
+
+        pdf._formattedDate = uploadDateObj.toLocaleDateString('en-US', {
+            year: 'numeric', month: 'short', day: 'numeric'
+        });
+
+        const timeDiff = now - uploadDateObj;
+        pdf._isNew = timeDiff < (7 * 24 * 60 * 60 * 1000); // 7 days
+    });
+}
+
 async function syncClassSwitcher() {
     const classSelect = document.getElementById('classSelect');
     if (!classSelect) return;
@@ -454,6 +483,7 @@ async function loadPDFDatabase() {
 
         if (shouldUseCache) {
             pdfDatabase = cachedData;
+            prepareSearchIndex(pdfDatabase);
             // --- FIX: CALL THIS TO POPULATE UI ---
             syncClassSwitcher();
             renderSemesterTabs();
@@ -477,8 +507,11 @@ async function loadPDFDatabase() {
             data: pdfDatabase
         }));
 
+        prepareSearchIndex(pdfDatabase);
         // --- FIX: CALL THIS TO POPULATE UI ---
         syncClassSwitcher();
+        renderSemesterTabs();
+        renderCategoryFilters();
         renderPDFs();
         hidePreloader();
 
@@ -905,26 +938,25 @@ 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);
+        // Optimize search using pre-calculated _searchStr
+        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 +1026,8 @@ 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
+    // Use pre-calculated values
+    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>`
@@ -1010,10 +1041,8 @@ 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'
-    });
+    // Use pre-calculated formatted date
+    const formattedDate = pdf._formattedDate || 'Unknown Date';
 
     // Uses global escapeHtml() now