diff --git a/.jules/bolt.md b/.jules/bolt.md
index 284d180a7..dc8b841e9 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -19,3 +19,6 @@
 ## 2026-07-13 - 단일 패스 문자열 치환 최적화 (O(N) 단일 스캔 및 지연 할당)
 **Learning:** `String.replace()`를 여러 번 체이닝하여 호출하면, 문자열 치환이 발생하지 않는 경우에도 내부적으로 불필요한 스캔이 중복 발생하고, 치환 시마다 새로운 문자열 객체와 char 배열이 할당되어 메모리 낭비와 성능 저하(GC 압박)가 발생한다.
 **Action:** 여러 문자를 한 번에 치환해야 하는 경우, O(N) 단일 스캔을 통해 `charAt()`으로 문자를 확인하고, 치환이 실제로 필요한 경우에만 `StringBuilder`를 지연 할당(Lazy allocation)하여 성능을 최적화하고 불필요한 메모리 할당을 방지한다.
+## 2026-10-05 - Batch DOM operations with DocumentFragment
+**Learning:** Appending DOM elements individually inside loops causes multiple reflows and repaints, which becomes a performance bottleneck for long lists or detailed views.
+**Action:** Always batch DOM updates using `DocumentFragment` before appending them to the active document tree to minimize rendering overhead.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1187deb2a..4ad11f8f5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,8 @@
 
 ### Changed
 
+- **프론트엔드 성능 최적화**: 뷰어 데모 스크립트(`demo.js`)에서 여러 DOM 엘리먼트를 반복적으로 추가할 때 리플로우(reflow)와 리페인트(repaint)를 줄이기 위해 `DocumentFragment`를 사용하도록 개선했습니다.
+
 - PDF.js WebJar를 `6.1.200`으로 올리고, Clearfolio가 동일 버전의 `pdf.mjs`와 `pdf.worker.mjs`를 직접 사용해 서명된 same-origin artifact의 첫 페이지를 렌더링하도록 통합했습니다. 패키징·셸 경로·서명된 `artifactToken` 흐름을 회귀 테스트로 고정했습니다.
 - CI가 pull request의 정확한 head SHA를 명시적으로 체크아웃하고 검증하며, 합성 merge revision은 별도 호환성 작업에서 검증하도록 분리했습니다.
 - Maven `verify` 단계에서 JaCoCo production line 및 branch missed count가 각각 0인지 강제하고, 실패 시 누락 위치 진단을 출력하도록 했습니다.
diff --git a/src/main/resources/static/assets/viewer/demo.js b/src/main/resources/static/assets/viewer/demo.js
index 42998be56..9e472de37 100644
--- a/src/main/resources/static/assets/viewer/demo.js
+++ b/src/main/resources/static/assets/viewer/demo.js
@@ -114,6 +114,9 @@ function renderHistory(history = loadHistory()) {
   el.historyBody.textContent = "";
   el.emptyHistory.hidden = history.length > 0;
 
+  // Optimized with DocumentFragment for performance
+  const fragment = document.createDocumentFragment();
+
   for (const job of history) {
     const row = document.createElement("tr");
     const fileCell = document.createElement("td");
@@ -143,18 +146,19 @@ function renderHistory(history = loadHistory()) {
     }
 
     row.append(fileCell, statusCell, submittedCell, actionsCell);
-    el.historyBody.appendChild(row);
+    fragment.appendChild(row);
   }
 
+  el.historyBody.appendChild(fragment);
   renderRecoveryEvidence(history);
 }
 
-function addDetailRow(label, value) {
+function addDetailRow(fragment, label, value) {
   const term = document.createElement("dt");
   const description = document.createElement("dd");
   term.textContent = label;
   description.textContent = formatDetailValue(value);
-  el.jobDetailBody.append(term, description);
+  fragment.append(term, description);
 }
 
 function formatDetailValue(value) {
@@ -177,17 +181,22 @@ function renderJobDetail(detail) {
     : "Operational evidence";
   el.jobDetailBody.textContent = "";
 
-  addDetailRow("Job ID", detail.jobId);
-  addDetailRow("Tenant", detail.tenantId);
-  addDetailRow("Status", detail.status);
-  addDetailRow("Message", detail.message);
-  addDetailRow("Attempts", `${detail.attemptCount ?? 0} / ${detail.maxAttempts ?? "n/a"}`);
-  addDetailRow("Dead-lettered", Boolean(detail.deadLettered));
-  addDetailRow("Retry at", detail.retryAt);
-  addDetailRow("Created", detail.createdAt);
-  addDetailRow("Started", detail.startedAt);
-  addDetailRow("Completed", detail.completedAt);
-  addDetailRow("Artifact", detail.convertedResourcePath);
+  // Optimized with DocumentFragment for performance
+  const fragment = document.createDocumentFragment();
+
+  addDetailRow(fragment, "Job ID", detail.jobId);
+  addDetailRow(fragment, "Tenant", detail.tenantId);
+  addDetailRow(fragment, "Status", detail.status);
+  addDetailRow(fragment, "Message", detail.message);
+  addDetailRow(fragment, "Attempts", `${detail.attemptCount ?? 0} / ${detail.maxAttempts ?? "n/a"}`);
+  addDetailRow(fragment, "Dead-lettered", Boolean(detail.deadLettered));
+  addDetailRow(fragment, "Retry at", detail.retryAt);
+  addDetailRow(fragment, "Created", detail.createdAt);
+  addDetailRow(fragment, "Started", detail.startedAt);
+  addDetailRow(fragment, "Completed", detail.completedAt);
+  addDetailRow(fragment, "Artifact", detail.convertedResourcePath);
+
+  el.jobDetailBody.appendChild(fragment);
 
   el.retryJobBtn.hidden = !detail.deadLettered;
 }
diff --git a/src/test/js/demo-integration.test.mjs b/src/test/js/demo-integration.test.mjs
index 0f0437ea2..dbf64f7f1 100644
--- a/src/test/js/demo-integration.test.mjs
+++ b/src/test/js/demo-integration.test.mjs
@@ -1,7 +1,7 @@
 import assert from "node:assert/strict";
 import test from "node:test";
 
-import { MockElement } from "./mock-dom.mjs";
+import { MockElement, MockDocumentFragment } from "./mock-dom.mjs";
 
 const elementIds = [
   "upload-form",
@@ -54,6 +54,9 @@ test("the executable demo renders inert actions and blocks repeated status activ
     createElement(tagName) {
       return new MockElement(tagName);
     },
+    createDocumentFragment() {
+      return new MockDocumentFragment();
+    },
   };
   globalThis.window = {
     confirm() {
diff --git a/src/test/js/dom-utils.test.mjs b/src/test/js/dom-utils.test.mjs
index 94b151063..9daf9358a 100644
--- a/src/test/js/dom-utils.test.mjs
+++ b/src/test/js/dom-utils.test.mjs
@@ -6,11 +6,14 @@ import {
   createLink,
   setBusyState
 } from "../../main/resources/static/assets/viewer/dom-utils.js";
-import { MockElement, MockTextNode } from "./mock-dom.mjs";
+import { MockElement, MockTextNode, MockDocumentFragment } from "./mock-dom.mjs";
 
 globalThis.document = {
   createElement(tagName) {
     return new MockElement(tagName);
+  },
+  createDocumentFragment() {
+    return new MockDocumentFragment();
   }
 };
 
diff --git a/src/test/js/mock-dom.mjs b/src/test/js/mock-dom.mjs
index 774116bc0..4b0e1a03f 100644
--- a/src/test/js/mock-dom.mjs
+++ b/src/test/js/mock-dom.mjs
@@ -31,12 +31,24 @@ export class MockElement {
   }
 
   appendChild(node) {
-    this.childNodes.push(node);
+    if (node instanceof MockDocumentFragment) {
+      this.childNodes.push(...node.childNodes);
+      node.childNodes = [];
+    } else {
+      this.childNodes.push(node);
+    }
     return node;
   }
 
   append(...nodes) {
-    this.childNodes.push(...nodes);
+    for (const node of nodes) {
+      if (node instanceof MockDocumentFragment) {
+        this.childNodes.push(...node.childNodes);
+        node.childNodes = [];
+      } else {
+        this.childNodes.push(node);
+      }
+    }
   }
 
   replaceChildren(...nodes) {
@@ -75,3 +87,17 @@ export class MockElement {
 
   reset() {}
 }
+
+export class MockDocumentFragment {
+  constructor() {
+    this.nodeType = 11;
+    this.childNodes = [];
+  }
+  appendChild(node) {
+    this.childNodes.push(node);
+    return node;
+  }
+  append(...nodes) {
+    this.childNodes.push(...nodes);
+  }
+}