diff --git a/js/util_worker_tasks.js b/js/util_worker_tasks.js
index 5aae7348e..2d9b98e32 100644
--- a/js/util_worker_tasks.js
+++ b/js/util_worker_tasks.js
@@ -3,6 +3,7 @@
 
 const functions = {
   arrayBufferToStringBase64,
+  fromBase64ToArrayBuffer,
 };
 
 onmessage = async e => {
@@ -36,3 +37,7 @@ function prepareErrorForPostMessage(error) {
 function arrayBufferToStringBase64(arrayBuffer) {
   return dcodeIO.ByteBuffer.wrap(arrayBuffer).toString('base64');
 }
+
+function fromBase64ToArrayBuffer(value) {
+  return dcodeIO.ByteBuffer.wrap(value, 'base64').toArrayBuffer();
+}
diff --git a/preload.js b/preload.js
index 5023abca0..e6875aa8b 100644
--- a/preload.js
+++ b/preload.js
@@ -296,7 +296,6 @@ const utilWorkerPath = path.join(app.getAppPath(), 'js', 'util_worker.js');
 const utilWorker = new WorkerInterface(utilWorkerPath, 3 * 60 * 1000);
 
 window.callWorker = (fnName, ...args) => utilWorker.callWorker(fnName, ...args);
-
 // Linux seems to periodically let the event loop stop, so this is a global workaround
 setInterval(() => {
   window.nodeSetImmediate(() => {});
diff --git a/ts/fileserver/FileServerApiV2.ts b/ts/fileserver/FileServerApiV2.ts
index 326f72a1e..d8c921cc7 100644
--- a/ts/fileserver/FileServerApiV2.ts
+++ b/ts/fileserver/FileServerApiV2.ts
@@ -1,7 +1,6 @@
 import { OpenGroupV2Request } from '../opengroup/opengroupV2/ApiUtil';
 import { sendApiV2Request } from '../opengroup/opengroupV2/OpenGroupAPIV2';
 import { parseStatusCodeFromOnionRequest } from '../opengroup/opengroupV2/OpenGroupAPIV2Parser';
-import { fromArrayBufferToBase64, fromBase64ToArrayBuffer } from '../session/utils/String';
 
 // tslint:disable-next-line: no-http-string
 export const oldFileServerV2URL = 'http://88.99.175.227';
@@ -41,7 +40,7 @@ export const uploadFileToFsV2 = async (
     return null;
   }
   const queryParams = {
-    file: fromArrayBufferToBase64(fileContent),
+    file: await window.callWorker('arrayBufferToStringBase64', fileContent),
   };
 
   const request: FileServerV2Request = {
@@ -110,7 +109,7 @@ export const downloadFileFromFSv2 = async (
   if (!base64Data) {
     return null;
   }
-  return fromBase64ToArrayBuffer(base64Data);
+  return window.callWorker('fromBase64ToArrayBuffer', base64Data);
 };
 
 /**
diff --git a/ts/opengroup/opengroupV2/ApiAuth.ts b/ts/opengroup/opengroupV2/ApiAuth.ts
index 77a21c774..cf1f94f40 100644
--- a/ts/opengroup/opengroupV2/ApiAuth.ts
+++ b/ts/opengroup/opengroupV2/ApiAuth.ts
@@ -153,8 +153,11 @@ export async function requestNewAuthToken({
     window?.log?.warn('Parsing failed');
     return null;
   }
-  const ciphertext = fromBase64ToArrayBuffer(base64EncodedCiphertext);
-  const ephemeralPublicKey = fromBase64ToArrayBuffer(base64EncodedEphemeralPublicKey);
+  const ciphertext = await window.callWorker('fromBase64ToArrayBuffer', base64EncodedCiphertext);
+  const ephemeralPublicKey = await window.callWorker(
+    'fromBase64ToArrayBuffer',
+    base64EncodedEphemeralPublicKey
+  );
   try {
     const symmetricKey = await window.libloki.crypto.deriveSymmetricKey(
       ephemeralPublicKey,
diff --git a/ts/opengroup/opengroupV2/ApiUtil.ts b/ts/opengroup/opengroupV2/ApiUtil.ts
index 4672447fe..c1613deae 100644
--- a/ts/opengroup/opengroupV2/ApiUtil.ts
+++ b/ts/opengroup/opengroupV2/ApiUtil.ts
@@ -47,7 +47,7 @@ export const parseMessages = async (
     window?.log?.info('no new messages');
     return [];
   }
-  const chunks = _.chunk(rawMessages, 10);
+  const chunks = _.chunk(rawMessages, 1000);
 
   const handleChunk = async (chunk: Array<Record<string, any>>) => {
     return Promise.all(
@@ -65,8 +65,14 @@ export const parseMessages = async (
           }
           // Validate the message signature
           const senderPubKey = PubKey.cast(opengroupv2Message.sender).withoutPrefix();
-          const signature = fromBase64ToArrayBuffer(opengroupv2Message.base64EncodedSignature);
-          const messageData = fromBase64ToArrayBuffer(opengroupv2Message.base64EncodedData);
+          const signature = await window.callWorker(
+            'fromBase64ToArrayBuffer',
+            opengroupv2Message.base64EncodedSignature
+          );
+          const messageData = await window.callWorker(
+            'fromBase64ToArrayBuffer',
+            opengroupv2Message.base64EncodedData
+          );
           // throws if signature failed
           await window.libsignal.Curve.async.verifySignature(
             fromHex(senderPubKey),
diff --git a/ts/opengroup/opengroupV2/OpenGroupAPIV2.ts b/ts/opengroup/opengroupV2/OpenGroupAPIV2.ts
index 944e8a009..4760808da 100644
--- a/ts/opengroup/opengroupV2/OpenGroupAPIV2.ts
+++ b/ts/opengroup/opengroupV2/OpenGroupAPIV2.ts
@@ -7,7 +7,6 @@ import {
 import { FSv2 } from '../../fileserver/';
 import { sendViaOnion } from '../../session/onions/onionSend';
 import { PubKey } from '../../session/types';
-import { fromArrayBufferToBase64, fromBase64ToArrayBuffer } from '../../session/utils/String';
 import { OpenGroupRequestCommonType, OpenGroupV2Info, OpenGroupV2Request } from './ApiUtil';
 import {
   parseMemberCount,
@@ -396,7 +395,7 @@ export const downloadFileOpenGroupV2 = async (
   if (!base64Data) {
     return null;
   }
-  return new Uint8Array(fromBase64ToArrayBuffer(base64Data));
+  return new Uint8Array(await window.callWorker('fromBase64ToArrayBuffer', base64Data));
 };
 
 export const downloadFileOpenGroupV2ByUrl = async (
@@ -423,7 +422,7 @@ export const downloadFileOpenGroupV2ByUrl = async (
   if (!base64Data) {
     return null;
   }
-  return new Uint8Array(fromBase64ToArrayBuffer(base64Data));
+  return new Uint8Array(await window.callWorker('fromBase64ToArrayBuffer', base64Data));
 };
 
 /**
@@ -469,7 +468,7 @@ export const uploadFileOpenGroupV2 = async (
     return null;
   }
   const queryParams = {
-    file: fromArrayBufferToBase64(fileContent),
+    file: await window.callWorker('arrayBufferToStringBase64', fileContent),
   };
 
   const filesEndpoint = 'files';
@@ -509,7 +508,7 @@ export const uploadImageForRoomOpenGroupV2 = async (
   }
 
   const queryParams = {
-    file: fromArrayBufferToBase64(fileContent),
+    file: await window.callWorker('arrayBufferToStringBase64', fileContent),
   };
 
   const imageEndpoint = `rooms/${roomInfos.roomId}/image`;
diff --git a/ts/opengroup/opengroupV2/OpenGroupMessageV2.ts b/ts/opengroup/opengroupV2/OpenGroupMessageV2.ts
index fd4481f90..96bb53bc7 100644
--- a/ts/opengroup/opengroupV2/OpenGroupMessageV2.ts
+++ b/ts/opengroup/opengroupV2/OpenGroupMessageV2.ts
@@ -1,12 +1,5 @@
-import { getSodium } from '../../session/crypto';
 import { UserUtils } from '../../session/utils';
-import {
-  fromArrayBufferToBase64,
-  fromBase64ToArray,
-  fromHex,
-  fromHexToArray,
-  toHex,
-} from '../../session/utils/String';
+import { fromBase64ToArray } from '../../session/utils/String';
 
 export class OpenGroupMessageV2 {
   public serverId?: number;
@@ -77,7 +70,7 @@ export class OpenGroupMessageV2 {
     return new OpenGroupMessageV2({
       base64EncodedData: this.base64EncodedData,
       sentTimestamp: this.sentTimestamp,
-      base64EncodedSignature: fromArrayBufferToBase64(signature),
+      base64EncodedSignature: await window.callWorker('arrayBufferToStringBase64', signature),
       sender: this.sender,
       serverId: this.serverId,
     });
diff --git a/ts/opengroup/opengroupV2/OpenGroupServerPoller.ts b/ts/opengroup/opengroupV2/OpenGroupServerPoller.ts
index 8dc67d5d3..44357bf75 100644
--- a/ts/opengroup/opengroupV2/OpenGroupServerPoller.ts
+++ b/ts/opengroup/opengroupV2/OpenGroupServerPoller.ts
@@ -480,7 +480,7 @@ const handleBase64AvatarUpdate = async (
 
         const upgradedAttachment = await processNewAttachment({
           isRaw: true,
-          data: fromBase64ToArrayBuffer(res.base64),
+          data: await window.callWorker('fromBase64ToArrayBuffer', res.base64),
           url: `${serverUrl}/${res.roomId}`,
         });
         // update the hash on the conversationModel
diff --git a/ts/opengroup/opengroupV2/OpenGroupUpdate.ts b/ts/opengroup/opengroupV2/OpenGroupUpdate.ts
index 2596a6d8f..3d47cb7c4 100644
--- a/ts/opengroup/opengroupV2/OpenGroupUpdate.ts
+++ b/ts/opengroup/opengroupV2/OpenGroupUpdate.ts
@@ -70,8 +70,6 @@ export async function updateOpenGroupV2(convo: ConversationModel, groupName: str
         isRaw: true,
         url: pathname,
       });
-      // FIXME audric update of roomname on the server?
-      window?.log?.warn('TODO update of roomName');
       const newHash = sha256(fromArrayBufferToBase64(downloaded.buffer));
       await convo.setLokiProfile({
         displayName: groupName || convo.get('name') || 'Unknown',
diff --git a/ts/pushnotification/PnServer.ts b/ts/pushnotification/PnServer.ts
index 3652e8168..7df502da9 100644
--- a/ts/pushnotification/PnServer.ts
+++ b/ts/pushnotification/PnServer.ts
@@ -1,5 +1,4 @@
 import { serverRequest } from '../session/onions/onionSend';
-import { fromArrayBufferToBase64 } from '../session/utils/String';
 
 const pnServerPubkeyHex = '642a6585919742e5a2d4dc51244964fbcd8bcab2b75612407de58b810740d049';
 
@@ -11,7 +10,7 @@ export async function notify(plainTextBuffer: ArrayBuffer, sentTo: string) {
   const options = {
     method: 'post',
     objBody: {
-      data: fromArrayBufferToBase64(plainTextBuffer),
+      data: await window.callWorker('arrayBufferToStringBase64', plainTextBuffer),
       send_to: sentTo,
     },
   };
diff --git a/ts/receiver/attachments.ts b/ts/receiver/attachments.ts
index 7be8d68ab..b1a7950b6 100644
--- a/ts/receiver/attachments.ts
+++ b/ts/receiver/attachments.ts
@@ -2,7 +2,6 @@ import _ from 'lodash';
 
 import { MessageModel } from '../models/message';
 import { saveMessage } from '../../ts/data/data';
-import { fromBase64ToArrayBuffer } from '../session/utils/String';
 import { AttachmentDownloads } from '../session/utils';
 import { ConversationModel } from '../models/conversation';
 import {
@@ -54,8 +53,8 @@ export async function downloadAttachment(attachment: any) {
 
     data = await window.textsecure.crypto.decryptAttachment(
       data,
-      fromBase64ToArrayBuffer(key),
-      fromBase64ToArrayBuffer(digest)
+      await window.callWorker('fromBase64ToArrayBuffer', key),
+      await window.callWorker('fromBase64ToArrayBuffer', digest)
     );
 
     if (!size || size !== data.byteLength) {
diff --git a/ts/session/snode_api/onions.ts b/ts/session/snode_api/onions.ts
index a4e81ed25..4bc691e2f 100644
--- a/ts/session/snode_api/onions.ts
+++ b/ts/session/snode_api/onions.ts
@@ -4,7 +4,7 @@ import https from 'https';
 import { dropSnodeFromSnodePool, dropSnodeFromSwarmIfNeeded, updateSwarmFor } from './snodePool';
 import ByteBuffer from 'bytebuffer';
 import { OnionPaths } from '../onions';
-import { fromBase64ToArrayBuffer, toHex } from '../utils/String';
+import {  toHex } from '../utils/String';
 import pRetry from 'p-retry';
 import { incrementBadPathCountOrDrop } from '../onions/onionPath';
 import _ from 'lodash';
@@ -395,7 +395,7 @@ export async function decodeOnionResult(symmetricKey: ArrayBuffer, ciphertext: s
   } catch (e) {
     // just try to get a json object from what is inside (for PN requests), if it fails, continue ()
   }
-  const ciphertextBuffer = fromBase64ToArrayBuffer(parsedCiphertext);
+  const ciphertextBuffer = await window.callWorker('fromBase64ToArrayBuffer', parsedCiphertext);
 
   const plaintextBuffer = await window.libloki.crypto.DecryptAESGCM(symmetricKey, ciphertextBuffer);
 
diff --git a/ts/session/utils/syncUtils.ts b/ts/session/utils/syncUtils.ts
index 33bff516a..a40be7046 100644
--- a/ts/session/utils/syncUtils.ts
+++ b/ts/session/utils/syncUtils.ts
@@ -14,14 +14,11 @@ import {
   ConfigurationMessageContact,
 } from '../messages/outgoing/controlMessage/ConfigurationMessage';
 import { ConversationModel } from '../../models/conversation';
-import { fromBase64ToArray, fromBase64ToArrayBuffer, fromHexToArray } from './String';
-import { fromBase64 } from 'bytebuffer';
+import { fromBase64ToArray } from './String';
 import { SignalService } from '../../protobuf';
 import _ from 'lodash';
 import {
-  AttachmentPointer,
   AttachmentPointerWithUrl,
-  Preview,
   PreviewWithAttachmentUrl,
   Quote,
   VisibleMessage,
diff --git a/ts/window.d.ts b/ts/window.d.ts
index d8a86a540..50297c1ed 100644
--- a/ts/window.d.ts
+++ b/ts/window.d.ts
@@ -84,5 +84,9 @@ declare global {
     LokiPushNotificationServer: any;
     globalOnlineStatus: boolean;
     confirmationDialog: any;
+    callWorker: (
+      fnName: 'arrayBufferToStringBase64' | 'fromBase64ToArrayBuffer',
+      ...args
+    ) => Promise<any>;
   }
 }