diff --git a/webAO/client/fetchLists.ts b/webAO/client/fetchLists.ts
index 9efd1817..a751ec07 100644
--- a/webAO/client/fetchLists.ts
+++ b/webAO/client/fetchLists.ts
@@ -1,6 +1,7 @@
 import { client } from "../client";
 import { AO_HOST } from "./aoHost";
 import { request } from "../services/request.js";
+import { canonicalizePath } from "../utils/paths";
 
 export const fetchBackgroundList = async () => {
     try {
@@ -27,7 +28,7 @@ export const fetchCharacterList = async () => {
     char_select.innerHTML = "";
 
     char_select.add(new Option("Custom", "0"));
-    
+
     try {
         const chardata = await request(`${AO_HOST}characters.json`);
         const char_array = JSON.parse(chardata);
@@ -58,7 +59,7 @@ export const fetchEvidenceList = async () => {
         evi_array.forEach((evi: string) => {
             evi_select.add(new Option(evi));
         });
-        
+
     } catch (err) {
         console.warn("there was no evidence.json file");
     }
@@ -68,10 +69,15 @@ export const fetchEvidenceList = async () => {
 export const fetchManifest = async () => {
     try {
         const manifestdata = await request(`${AO_HOST}manifest.txt`);
-        client.manifest = manifestdata.split(/\r\n|\n\r|\n|\r/);
+        const tmp: string[] = manifestdata
+            .replace("\\", "/")
+            .split(/\r\n|\n\r|\n|\r/);
+        client.manifest = tmp.map(x => canonicalizePath(x)).sort();
+
         // the try catch will fail before here when there is no file
 
     } catch (err) {
-        console.warn("there was no manifest.txt file");
+        console.warn("no manifest.txt, webao will be slow");
+        client.manifest = [];
     }
-}
\ No newline at end of file
+}
diff --git a/webAO/client/handleCharacterInfo.ts b/webAO/client/handleCharacterInfo.ts
index 9d74a8bc..f2d9bfcb 100644
--- a/webAO/client/handleCharacterInfo.ts
+++ b/webAO/client/handleCharacterInfo.ts
@@ -2,7 +2,7 @@ import { client } from "../client";
 import { safeTags } from "../encoding";
 import iniParse from "../iniParse";
 import request from "../services/request";
-import fileExists from "../utils/fileExists";
+import { fileExistsManifest } from "../utils/fileExists";
 import { AO_HOST } from "./aoHost";
 
 
@@ -23,7 +23,7 @@ export const handleCharacterInfo = async (chargs: string[], charid: number) => {
             )}/char_icon`;
             for (let i = 0; i < extensions.length; i++) {
                 const fileUrl = charIconBaseUrl + extensions[i];
-                const exists = await fileExists(fileUrl);
+                const exists = await fileExistsManifest(fileUrl);
                 if (exists) {
                     img.alt = chargs[0];
                     img.title = chargs[0];
@@ -102,4 +102,4 @@ export const handleCharacterInfo = async (chargs: string[], charid: number) => {
         console.warn(`missing charid ${charid}`);
         img.style.display = "none";
     }
-}
\ No newline at end of file
+}
diff --git a/webAO/client/setEmote.ts b/webAO/client/setEmote.ts
index f4fbdbb1..41fe6b51 100644
--- a/webAO/client/setEmote.ts
+++ b/webAO/client/setEmote.ts
@@ -1,6 +1,6 @@
 import Client from "../client";
 import transparentPng from "../constants/transparentPng";
-import fileExists from "../utils/fileExists";
+import {fileExistsManifest} from "../utils/fileExists";
 
 /**
  * Sets all the img tags to the right sources
@@ -39,13 +39,14 @@ const setEmote = async (
     } else if (extension === ".webp.static") {
       url = `${characterFolder}${encodeURI(charactername)}/${encodeURI(
         emotename
-      )}.webp`;    
+      )}.webp`;
     } else {
       url = `${characterFolder}${encodeURI(charactername)}/${encodeURI(
         prefix
       )}${encodeURI(emotename)}${extension}`;
     }
-    const exists = await fileExists(url);
+
+    const exists = await fileExistsManifest(url);
     if (exists) {
       emoteSelector.src = url;
       break;
diff --git a/webAO/packets/handlers/handlePV.ts b/webAO/packets/handlers/handlePV.ts
index 3c669b96..affabbed 100644
--- a/webAO/packets/handlers/handlePV.ts
+++ b/webAO/packets/handlers/handlePV.ts
@@ -1,5 +1,5 @@
 import { client } from "../../client";
-import fileExists from "../../utils/fileExists";
+import { fileExistsManifest } from "../../utils/fileExists";
 import { updateActionCommands } from '../../dom/updateActionCommands'
 import { pickEmotion } from '../../dom/pickEmotion'
 import { AO_HOST } from "../../client/aoHost";
@@ -73,8 +73,8 @@ export const handlePV = async (args: string[]) => {
   }
 
   if (
-    await fileExists(
-      `${AO_HOST}characters/${encodeURI(me.name.toLowerCase())}/custom.gif`
+    await fileExistsManifest(
+      `characters/${encodeURI(me.name.toLowerCase())}/custom.gif`
     )
   ) {
     document.getElementById("button_4")!.style.display = "";
diff --git a/webAO/utils/binarySearch.js b/webAO/utils/binarySearch.js
new file mode 100644
index 00000000..7ffbf1a1
--- /dev/null
+++ b/webAO/utils/binarySearch.js
@@ -0,0 +1,21 @@
+/* Returns the index of `needle' in `haystack', or `null' if it wasn't found. */
+export function binarySearch(haystack,
+                             needle,
+                             cmp = (a, b) => a < b ? -1 : a > b ? 1 : 0) {
+    let start = 0;
+    let end = haystack.length - 1;
+
+    while (start <= end) {
+        const middle = Math.floor((start + end) / 2);
+        const comparison = cmp(haystack[middle], needle);
+
+        if (comparison == 0)
+            return middle;
+        else if (comparison < 0)
+            start = middle + 1;
+        else
+            end = middle - 1;
+    }
+
+    return null;
+}
diff --git a/webAO/utils/fileExists.js b/webAO/utils/fileExists.js
index 7978cbc6..dab41072 100644
--- a/webAO/utils/fileExists.js
+++ b/webAO/utils/fileExists.js
@@ -1,3 +1,8 @@
+import {AO_HOST} from "../client/aoHost"
+import {client} from "../client"
+import {canonicalizePath} from "./paths"
+import {binarySearch} from "./binarySearch"
+
 const fileExists = async (url) => new Promise((resolve, reject) => {
   const xhr = new XMLHttpRequest();
   xhr.open('HEAD', url);
@@ -16,3 +21,22 @@ const fileExists = async (url) => new Promise((resolve, reject) => {
   xhr.send(null);
 });
 export default fileExists;
+
+/* Returns whether file exists.
+ * `url' is a URL, including the base URL for bw compat.
+ * If manifest is empty, check the old way.
+ * Otherwise, look it up in the manifest */
+const fileExistsManifest = async (url) =>
+      new Promise((resolve, reject) => {
+          if(client.manifest.length == 0) {
+              resolve(fileExists(url));
+              return;
+          }
+          const c_url = encodeURI(canonicalizePath(decodeURI(url.slice(AO_HOST.length))));
+
+          if(binarySearch(client.manifest, c_url) != null)
+              resolve(true);
+
+          resolve(false);
+      });
+export {fileExistsManifest};
diff --git a/webAO/utils/getAnimLength.js b/webAO/utils/getAnimLength.js
index aa303cfb..4eae58fa 100644
--- a/webAO/utils/getAnimLength.js
+++ b/webAO/utils/getAnimLength.js
@@ -1,5 +1,7 @@
+import {client} from '../client'
+import {AO_HOST} from '../client/aoHost'
 import calculatorHandler from './calculatorHandler';
-import fileExists from './fileExists.js';
+import {fileExistsManifest} from './fileExists.js';
 import { requestBuffer } from '../services/request.js';
 /**
 	 * Gets animation length. If the animation cannot be found, it will
@@ -11,7 +13,7 @@ const getAnimLength = async (url) => {
   const extensions = ['.gif', '.webp', '.apng'];
   for (const extension of extensions) {
     const urlWithExtension = url + extension;
-    const exists = await fileExists(urlWithExtension);
+      const exists = await fileExistsManifest(urlWithExtension);
     if (exists) {
       const fileBuffer = await requestBuffer(urlWithExtension);
       const length = calculatorHandler[extension](fileBuffer);
diff --git a/webAO/utils/paths.ts b/webAO/utils/paths.ts
index f4284b66..9cf4f197 100644
--- a/webAO/utils/paths.ts
+++ b/webAO/utils/paths.ts
@@ -1 +1,20 @@
 export const getFilenameFromPath = (path: string) => path.substring(path.lastIndexOf('/') + 1)
+
+/* Removes `/./`, `/../`, and `//`.
+ * Does not add a leading `/` or `./`.
+ * Does not add a trailing `/`. */
+export function canonicalizePath(path: string): string {
+  const path_elements = path.split("/");
+  var result: string[] = [];
+
+  for (const el of path_elements) {
+    if (el === "..")
+      result.pop();
+    else if (el === "." || el === "")
+      continue;
+
+    result.push(el);
+  }
+
+  return result.join("/");
+}
diff --git a/webAO/utils/tryUrls.ts b/webAO/utils/tryUrls.ts
index 14ef8852..1e5107f7 100644
--- a/webAO/utils/tryUrls.ts
+++ b/webAO/utils/tryUrls.ts
@@ -1,4 +1,4 @@
-import fileExists from './fileExists'
+import {fileExistsManifest} from './fileExists'
 import transparentPng from '../constants/transparentPng'
 const urlExtensionsToTry = [
     '.png',
@@ -10,11 +10,11 @@ const tryUrls = async (url: string) => {
     for (let i = 0; i < urlExtensionsToTry.length; i++) {
         const extension = urlExtensionsToTry[i]
         const fullFileUrl = url + extension
-        const exists = await fileExists(fullFileUrl);
+        const exists = await fileExistsManifest(fullFileUrl);
         if (exists) {
             return fullFileUrl
         }
     }
     return transparentPng
 }
-export default tryUrls
\ No newline at end of file
+export default tryUrls
diff --git a/webAO/viewport/utils/setSide.ts b/webAO/viewport/utils/setSide.ts
index 3726e83d..69018227 100644
--- a/webAO/viewport/utils/setSide.ts
+++ b/webAO/viewport/utils/setSide.ts
@@ -2,7 +2,7 @@ import { positions } from '../constants/positions'
 import { AO_HOST } from '../../client/aoHost'
 import { client } from '../../client'
 import tryUrls from '../../utils/tryUrls';
-import fileExists from '../../utils/fileExists';
+import { fileExistsManifest } from '../../utils/fileExists';
 
 /**
  * Changes the viewport background based on a given position.
@@ -57,10 +57,12 @@ export const set_side = async ({
     } else {
         court.src = await tryUrls(client.viewport.getBackgroundFolder() + bg);
     }
-    
-    
+
+
     if (showDesk === true && desk) {
-        const deskFilename = (await fileExists(client.viewport.getBackgroundFolder() + desk.ao2))
+        const deskFilename = (await fileExistsManifest(
+          (client.viewport.getBackgroundFolder() +
+            desk.ao2)))
             ? desk.ao2
             : desk.ao1;
         bench.src = client.viewport.getBackgroundFolder() + deskFilename;