diff --git a/static/js/cours.js b/static/js/cours.js
index 6537fad..8800b14 100644
--- a/static/js/cours.js
+++ b/static/js/cours.js
@@ -92,31 +92,35 @@ const deepestNodeOpened = (path, options) => {
 };
 
 const searchFiles = (query, parent, currentFile) => {
-  const children = parent.querySelectorAll("li");
+  // Prevent blocking the main thread
+  requestAnimationFrame(() => {
+    const children = parent.querySelectorAll("li");
 
-  if (query === "") {
-    children.forEach((item) => {
-      item.style.display = "";
-      if (
-        item.classList.contains("directory") &&
-        !item.classList.contains("collapsed")
-      ) {
-        item.classList.add("collapsed");
-      }
-    });
-
-    uncollapse(currentFile);
-    return;
-  }
-
-  for (const item of children) {
-    if (item.innerText.toLowerCase().includes(query.toLowerCase())) {
-      item.style.display = "";
-      uncollapse(item);
-      continue;
+    const normalizedQuery = query.toLowerCase().trim();
+    if (normalizedQuery === "") {
+      children.forEach((item) => {
+        item.style.display = "";
+        if (
+          item.classList.contains("directory") &&
+          !item.classList.contains("collapsed")
+        ) {
+          item.classList.add("collapsed");
+        }
+      });
+      uncollapse(currentFile);
+      return;
     }
-    item.style.display = "none";
-  }
+
+    for (const item of children) {
+      const matches = item.innerText.toLowerCase().includes(normalizedQuery);
+      if (matches) {
+        item.style.display = "";
+        uncollapse(item);
+        continue;
+      }
+      item.style.display = "none";
+    }
+  });
 };
 
 window.addEventListener("load", () => {