diff --git a/keyserver/src/creators/message-report-creator.js b/keyserver/src/creators/message-report-creator.js
--- a/keyserver/src/creators/message-report-creator.js
+++ b/keyserver/src/creators/message-report-creator.js
@@ -75,26 +75,24 @@
     viewer,
     request.messageID,
   );
-  const promises = {};
-
-  promises.viewerUsername = fetchUsername(viewer.id);
+  const viewerUsernamePromise = fetchUsername(viewer.id);
 
   const keyserverAdminID = await keyserverAdminIDPromise;
   if (!keyserverAdminID) {
     throw new ServerError('keyserver_admin_not_found');
   }
-  promises.commbotThreadID = getCommbotThreadID(keyserverAdminID);
+  const commbotThreadIDPromise = getCommbotThreadID(keyserverAdminID);
 
   const reportedMessage = await reportedMessagePromise;
 
-  if (reportedMessage) {
-    promises.reportedThread = serverThreadInfoFromMessageInfo(reportedMessage);
-  }
+  const reportedThreadPromise: Promise<?ServerThreadInfo> = reportedMessage
+    ? serverThreadInfoFromMessageInfo(reportedMessage)
+    : Promise.resolve(undefined);
 
   const reportedMessageAuthorID = reportedMessage?.creatorID;
-  if (reportedMessageAuthorID) {
-    promises.reportedMessageAuthor = fetchUsername(reportedMessageAuthorID);
-  }
+  const reportedMessageAuthorPromise: Promise<?string> = reportedMessageAuthorID
+    ? fetchUsername(reportedMessageAuthorID)
+    : Promise.resolve(undefined);
 
   const reportedMessageText =
     reportedMessage?.type === 0 ? reportedMessage.text : null;
@@ -104,7 +102,12 @@
     commbotThreadID,
     reportedThread,
     reportedMessageAuthor,
-  } = await promiseAll(promises);
+  } = await promiseAll({
+    viewerUsername: viewerUsernamePromise,
+    commbotThreadID: commbotThreadIDPromise,
+    reportedThread: reportedThreadPromise,
+    reportedMessageAuthor: reportedMessageAuthorPromise,
+  });
 
   return {
     reportedMessageText,
diff --git a/keyserver/src/creators/thread-creator.js b/keyserver/src/creators/thread-creator.js
--- a/keyserver/src/creators/thread-creator.js
+++ b/keyserver/src/creators/thread-creator.js
@@ -185,18 +185,19 @@
     return { initialMemberIDs, ghostMemberIDs };
   })();
 
-  const checkPromises = {};
-  checkPromises.confirmParentPermission = confirmParentPermissionPromise;
-  checkPromises.threadAncestry = determineThreadAncestryPromise;
-  checkPromises.validateMembers = validateMembersPromise;
-  if (sourceMessageID) {
-    checkPromises.sourceMessage = fetchMessageInfoByID(viewer, sourceMessageID);
-  }
+  const sourceMessagePromise: Promise<?RawMessageInfo> = sourceMessageID
+    ? fetchMessageInfoByID(viewer, sourceMessageID)
+    : Promise.resolve(undefined);
   const {
     sourceMessage,
     threadAncestry,
     validateMembers: { initialMemberIDs, ghostMemberIDs },
-  } = await promiseAll(checkPromises);
+  } = await promiseAll({
+    sourceMessage: sourceMessagePromise,
+    threadAncestry: determineThreadAncestryPromise,
+    validateMembers: validateMembersPromise,
+    confirmParentPermission: confirmParentPermissionPromise,
+  });
 
   if (sourceMessage && isInvalidSidebarSource(sourceMessage)) {
     throw new ServerError('invalid_parameters');
diff --git a/keyserver/src/creators/update-creator.js b/keyserver/src/creators/update-creator.js
--- a/keyserver/src/creators/update-creator.js
+++ b/keyserver/src/creators/update-creator.js
@@ -16,11 +16,14 @@
 import {
   type CalendarQuery,
   defaultCalendarQuery,
+  type RawEntryInfos,
   type RawEntryInfo,
+  type FetchEntryInfosBase,
 } from 'lib/types/entry-types.js';
 import {
   defaultNumberPerThread,
   type MessageSelectionCriteria,
+  type FetchMessageInfosResult,
   type RawMessageInfo,
 } from 'lib/types/message-types.js';
 import {
@@ -35,7 +38,7 @@
   type RawUpdateInfo,
   type CreateUpdatesResult,
 } from 'lib/types/update-types.js';
-import type { UserInfos } from 'lib/types/user-types.js';
+import type { UserInfos, LoggedInUserInfo } from 'lib/types/user-types.js';
 import { promiseAll } from 'lib/utils/promises.js';
 
 import createIDs from './id-creator.js';
@@ -47,7 +50,10 @@
   fetchEntryInfosByID,
 } from '../fetchers/entry-fetchers.js';
 import { fetchMessageInfos } from '../fetchers/message-fetchers.js';
-import { fetchThreadInfos } from '../fetchers/thread-fetchers.js';
+import {
+  fetchThreadInfos,
+  type FetchThreadInfosResult,
+} from '../fetchers/thread-fetchers.js';
 import {
   fetchKnownUserInfos,
   fetchCurrentUserInfo,
@@ -337,39 +343,50 @@
     deleteSQLConditions.push(mergeAndConditions(sqlConditions));
   }
 
-  const promises = {};
-
-  if (insertRows.length > 0) {
+  const insertPromise = (async () => {
+    if (insertRows.length === 0) {
+      return;
+    }
     const insertQuery = SQL`
       INSERT INTO updates(id, user, type, \`key\`,
         content, time, updater, target)
     `;
     insertQuery.append(SQL`VALUES ${insertRows}`);
-    promises.insert = dbQuery(insertQuery);
-  }
+    await dbQuery(insertQuery);
+  })();
 
-  if (publishInfos.size > 0) {
-    promises.redis = redisPublish(publishInfos.values(), dontBroadcastSession);
-  }
+  const redisPromise =
+    publishInfos.size > 0
+      ? redisPublish(publishInfos.values(), dontBroadcastSession)
+      : Promise.resolve(undefined);
 
-  if (deleteSQLConditions.length > 0) {
-    promises.delete = (async () => {
-      while (deleteSQLConditions.length > 0) {
-        const batch = deleteSQLConditions.splice(0, deleteUpdatesBatchSize);
-        await deleteUpdatesByConditions(batch);
-      }
-    })();
-  }
+  const deletePromise = (async () => {
+    if (deleteSQLConditions.length === 0) {
+      return;
+    }
+    while (deleteSQLConditions.length > 0) {
+      const batch = deleteSQLConditions.splice(0, deleteUpdatesBatchSize);
+      await deleteUpdatesByConditions(batch);
+    }
+  })();
 
-  if (viewerRawUpdateInfos.length > 0) {
+  const updatesPromise: Promise<?FetchUpdatesResult> = (async () => {
+    if (viewerRawUpdateInfos.length === 0) {
+      return undefined;
+    }
     invariant(viewerInfo, 'should be set');
-    promises.updatesResult = fetchUpdateInfosWithRawUpdateInfos(
+    return await fetchUpdateInfosWithRawUpdateInfos(
       viewerRawUpdateInfos,
       viewerInfo,
     );
-  }
+  })();
 
-  const { updatesResult } = await promiseAll(promises);
+  const { updatesResult } = await promiseAll({
+    updatesResult: updatesPromise,
+    insertResult: insertPromise,
+    redisResult: redisPromise,
+    deleteResult: deletePromise,
+  });
   if (!updatesResult) {
     return defaultUpdateCreationResult;
   }
@@ -407,27 +424,31 @@
     entitiesToFetch.map(({ userID }) => userID).filter(Boolean),
   );
 
-  const promises = {};
-
   const { viewer } = viewerInfo;
-  if (!viewerInfo.threadInfos && threadIDsNeedingFetch.size > 0) {
-    promises.threadResult = fetchThreadInfos(viewer, {
+  const threadPromise: Promise<?FetchThreadInfosResult> = (async () => {
+    if (viewerInfo.threadInfos || threadIDsNeedingFetch.size === 0) {
+      return undefined;
+    }
+    return await fetchThreadInfos(viewer, {
       threadIDs: threadIDsNeedingFetch,
     });
-  }
+  })();
 
-  let calendarQuery: ?CalendarQuery = viewerInfo.calendarQuery
-    ? viewerInfo.calendarQuery
-    : null;
-  if (!calendarQuery && viewer.hasSessionInfo) {
+  let calendarQueryTmp: ?CalendarQuery = viewerInfo.calendarQuery ?? null;
+  if (!calendarQueryTmp && viewer.hasSessionInfo) {
     // This should only ever happen for "legacy" clients who call in without
     // providing this information. These clients wouldn't know how to deal with
     // the corresponding UpdateInfos anyways, so no reason to be worried.
-    calendarQuery = viewer.calendarQuery;
-  } else if (!calendarQuery) {
-    calendarQuery = defaultCalendarQuery(viewer.platform, viewer.timeZone);
+    calendarQueryTmp = viewer.calendarQuery;
+  } else if (!calendarQueryTmp) {
+    calendarQueryTmp = defaultCalendarQuery(viewer.platform, viewer.timeZone);
   }
-  if (threadIDsNeedingDetailedFetch.size > 0) {
+  const calendarQuery = calendarQueryTmp;
+
+  const messageInfosPromise: Promise<?FetchMessageInfosResult> = (async () => {
+    if (threadIDsNeedingDetailedFetch.size === 0) {
+      return undefined;
+    }
     const threadCursors: { [string]: ?string } = {};
     for (const threadID of threadIDsNeedingDetailedFetch) {
       threadCursors[threadID] = null;
@@ -435,11 +456,17 @@
     const messageSelectionCriteria: MessageSelectionCriteria = {
       threadCursors,
     };
-    promises.messageInfosResult = fetchMessageInfos(
+    return await fetchMessageInfos(
       viewer,
       messageSelectionCriteria,
       defaultNumberPerThread,
     );
+  })();
+
+  const calendarPromise: Promise<?FetchEntryInfosBase> = (async () => {
+    if (threadIDsNeedingDetailedFetch.size === 0) {
+      return undefined;
+    }
     const threadCalendarQuery = {
       ...calendarQuery,
       filters: [
@@ -447,27 +474,31 @@
         { type: 'threads', threadIDs: [...threadIDsNeedingDetailedFetch] },
       ],
     };
-    promises.calendarResult = fetchEntryInfos(viewer, [threadCalendarQuery]);
-  }
+    return await fetchEntryInfos(viewer, [threadCalendarQuery]);
+  })();
 
-  if (entryIDsNeedingFetch.size > 0) {
-    promises.entryInfosResult = fetchEntryInfosByID(
-      viewer,
-      entryIDsNeedingFetch,
-    );
-  }
-
-  if (currentUserNeedsFetch) {
-    promises.currentUserInfoResult = (async () => {
-      const currentUserInfo = await fetchCurrentUserInfo(viewer);
-      invariant(currentUserInfo.anonymous === undefined, 'should be logged in');
-      return currentUserInfo;
-    })();
-  }
+  const entryInfosPromise: Promise<?RawEntryInfos> = (async () => {
+    if (entryIDsNeedingFetch.size === 0) {
+      return undefined;
+    }
+    return await fetchEntryInfosByID(viewer, entryIDsNeedingFetch);
+  })();
 
-  if (userIDsToFetch.size > 0) {
-    promises.userInfosResult = fetchKnownUserInfos(viewer, [...userIDsToFetch]);
-  }
+  const currentUserInfoPromise: Promise<?LoggedInUserInfo> = (async () => {
+    if (!currentUserNeedsFetch) {
+      return undefined;
+    }
+    const currentUserInfo = await fetchCurrentUserInfo(viewer);
+    invariant(currentUserInfo.anonymous === undefined, 'should be logged in');
+    return currentUserInfo;
+  })();
+
+  const userInfosPromise: Promise<?UserInfos> = (async () => {
+    if (userIDsToFetch.size === 0) {
+      return undefined;
+    }
+    return await fetchKnownUserInfos(viewer, [...userIDsToFetch]);
+  })();
 
   const {
     threadResult,
@@ -476,7 +507,14 @@
     entryInfosResult,
     currentUserInfoResult,
     userInfosResult,
-  } = await promiseAll(promises);
+  } = await promiseAll({
+    threadResult: threadPromise,
+    messageInfosResult: messageInfosPromise,
+    calendarResult: calendarPromise,
+    entryInfosResult: entryInfosPromise,
+    currentUserInfoResult: currentUserInfoPromise,
+    userInfosResult: userInfosPromise,
+  });
 
   let threadInfos = {};
   if (viewerInfo.threadInfos) {
diff --git a/keyserver/src/deleters/account-deleters.js b/keyserver/src/deleters/account-deleters.js
--- a/keyserver/src/deleters/account-deleters.js
+++ b/keyserver/src/deleters/account-deleters.js
@@ -19,7 +19,7 @@
 import { rescindPushNotifs } from '../push/rescind.js';
 import { handleAsyncPromise } from '../responders/handlers.js';
 import { createNewAnonymousCookie } from '../session/cookies.js';
-import type { Viewer } from '../session/viewer.js';
+import type { Viewer, AnonymousViewerData } from '../session/viewer.js';
 import { fetchOlmAccount } from '../updaters/olm-account-updater.js';
 
 async function deleteAccount(viewer: Viewer): Promise<?LogOutResponse> {
@@ -72,16 +72,23 @@
     COMMIT;
   `;
 
-  const promises = {};
-  promises.deletion = dbQuery(deletionQuery, { multipleStatements: true });
-  if (!viewer.isScriptViewer) {
-    promises.anonymousViewerData = createNewAnonymousCookie({
-      platformDetails: viewer.platformDetails,
-      deviceToken: viewer.deviceToken,
-    });
-  }
-  promises.username = fetchUsername(deletedUserID);
-  const { anonymousViewerData, username } = await promiseAll(promises);
+  const deletionPromise = dbQuery(deletionQuery, { multipleStatements: true });
+  const anonymousViewerDataPromise: Promise<?AnonymousViewerData> =
+    (async () => {
+      if (viewer.isScriptViewer) {
+        return undefined;
+      }
+      return await createNewAnonymousCookie({
+        platformDetails: viewer.platformDetails,
+        deviceToken: viewer.deviceToken,
+      });
+    })();
+  const usernamePromise = fetchUsername(deletedUserID);
+  const { anonymousViewerData, username } = await promiseAll({
+    anonymousViewerData: anonymousViewerDataPromise,
+    username: usernamePromise,
+    deletion: deletionPromise,
+  });
   if (username) {
     const issuedAt = new Date().toISOString();
     const reservedUsernameMessage: ReservedUsernameMessage = {
diff --git a/keyserver/src/fetchers/thread-fetchers.js b/keyserver/src/fetchers/thread-fetchers.js
--- a/keyserver/src/fetchers/thread-fetchers.js
+++ b/keyserver/src/fetchers/thread-fetchers.js
@@ -245,7 +245,7 @@
   return { threadInfos };
 }
 
-type FetchThreadInfosResult = {
+export type FetchThreadInfosResult = {
   +threadInfos: RawThreadInfos,
 };
 
diff --git a/keyserver/src/push/rescind.js b/keyserver/src/push/rescind.js
--- a/keyserver/src/push/rescind.js
+++ b/keyserver/src/push/rescind.js
@@ -192,18 +192,28 @@
   }
 
   const numRescinds = Object.keys(deliveryPromises).length;
-  const promises = [promiseAll(deliveryPromises)];
-  if (numRescinds > 0) {
-    promises.push(createIDs('notifications', numRescinds));
-  }
-  if (rescindedIDs.length > 0) {
+  const dbIDsPromise: Promise<?Array<string>> = (async () => {
+    if (numRescinds === 0) {
+      return undefined;
+    }
+    return await createIDs('notifications', numRescinds);
+  })();
+  const rescindPromise: Promise<mixed> = (async () => {
+    if (rescindedIDs.length === 0) {
+      return undefined;
+    }
     const rescindQuery = SQL`
       UPDATE notifications SET rescinded = 1 WHERE id IN (${rescindedIDs})
     `;
-    promises.push(dbQuery(rescindQuery));
-  }
+    return await dbQuery(rescindQuery);
+  })();
+
+  const [deliveryResults, dbIDs] = await Promise.all([
+    promiseAll(deliveryPromises),
+    dbIDsPromise,
+    rescindPromise,
+  ]);
 
-  const [deliveryResults, dbIDs] = await Promise.all(promises);
   const newNotifRows = [];
   if (numRescinds > 0) {
     invariant(dbIDs, 'dbIDs should be set');
diff --git a/keyserver/src/push/send.js b/keyserver/src/push/send.js
--- a/keyserver/src/push/send.js
+++ b/keyserver/src/push/send.js
@@ -8,6 +8,7 @@
 import _groupBy from 'lodash/fp/groupBy.js';
 import _mapValues from 'lodash/fp/mapValues.js';
 import _pickBy from 'lodash/fp/pickBy.js';
+import type { QueryResults } from 'mysql';
 import t from 'tcomb';
 import uuidv4 from 'uuid/v4.js';
 
@@ -46,7 +47,6 @@
 import { type GlobalUserInfo } from 'lib/types/user-types.js';
 import { isDev } from 'lib/utils/dev-utils.js';
 import { values } from 'lib/utils/objects.js';
-import { promiseAll } from 'lib/utils/promises.js';
 import { tID, tPlatformDetails, tShape } from 'lib/utils/validation-utils.js';
 
 import {
@@ -696,10 +696,13 @@
     }
   }
 
-  const promises = {};
   // These threadInfos won't have currentUser set
-  promises.threadResult = fetchServerThreadInfos({ threadIDs });
-  if (threadWithChangedNamesToMessages.size > 0) {
+  const threadPromise = fetchServerThreadInfos({ threadIDs });
+
+  const oldNamesPromise: Promise<?QueryResults> = (async () => {
+    if (threadWithChangedNamesToMessages.size === 0) {
+      return undefined;
+    }
     const typesThatAffectName = [
       messageTypes.CHANGE_SETTINGS,
       messageTypes.CREATE_THREAD,
@@ -728,10 +731,13 @@
       ) x
       LEFT JOIN messages m ON m.id = x.id
     `);
-    promises.oldNames = dbQuery(oldNameQuery);
-  }
+    return await dbQuery(oldNameQuery);
+  })();
 
-  const { threadResult, oldNames } = await promiseAll(promises);
+  const [threadResult, oldNames] = await Promise.all([
+    threadPromise,
+    oldNamesPromise,
+  ]);
   const serverThreadInfos = threadResult.threadInfos;
   if (oldNames) {
     const [result] = oldNames;
diff --git a/keyserver/src/responders/redux-state-responders.js b/keyserver/src/responders/redux-state-responders.js
--- a/keyserver/src/responders/redux-state-responders.js
+++ b/keyserver/src/responders/redux-state-responders.js
@@ -23,6 +23,7 @@
 import {
   defaultNumberPerThread,
   messageStoreValidator,
+  type MessageStore,
 } from 'lib/types/message-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
 import { threadTypes } from 'lib/types/thread-types-enum.js';
@@ -153,7 +154,7 @@
     ]);
     return { threadInfos: hasNotAcknowledgedPolicies ? {} : threadInfos };
   })();
-  const messageStorePromise = (async () => {
+  const messageStorePromise: Promise<MessageStore> = (async () => {
     const [
       { threadInfos },
       { rawMessageInfos, truncationStatuses },
@@ -287,7 +288,7 @@
     return hasNotAcknowledgedPolicies ? 0 : initialTime;
   })();
 
-  const pushApiPublicKeyPromise = (async () => {
+  const pushApiPublicKeyPromise: Promise<?string> = (async () => {
     const pushConfig = await getWebPushConfig();
     if (!pushConfig) {
       if (process.env.NODE_ENV !== 'development') {
diff --git a/keyserver/src/responders/user-responders.js b/keyserver/src/responders/user-responders.js
--- a/keyserver/src/responders/user-responders.js
+++ b/keyserver/src/responders/user-responders.js
@@ -43,6 +43,7 @@
 import {
   type CalendarQuery,
   rawEntryInfoValidator,
+  type FetchEntryInfosBase,
 } from 'lib/types/entry-types.js';
 import {
   defaultNumberPerThread,
@@ -73,7 +74,6 @@
 } from 'lib/utils/crypto-utils.js';
 import { ServerError } from 'lib/utils/errors.js';
 import { values } from 'lib/utils/objects.js';
-import { promiseAll } from 'lib/utils/promises.js';
 import {
   getPublicKeyFromSIWEStatement,
   isValidSIWEMessage,
@@ -362,6 +362,13 @@
   }
   const messageSelectionCriteria = { threadCursors, joinedThreads: true };
 
+  const entriesPromise: Promise<?FetchEntryInfosBase> = (async () => {
+    if (!calendarQuery) {
+      return undefined;
+    }
+    return await fetchEntryInfos(viewer, [calendarQuery]);
+  })();
+
   const [
     threadsResult,
     messagesResult,
@@ -371,7 +378,7 @@
   ] = await Promise.all([
     fetchThreadInfos(viewer),
     fetchMessageInfos(viewer, messageSelectionCriteria, defaultNumberPerThread),
-    calendarQuery ? fetchEntryInfos(viewer, [calendarQuery]) : undefined,
+    entriesPromise,
     fetchKnownUserInfos(viewer),
     fetchLoggedInUserInfo(viewer),
     olmSessionPromise,
@@ -455,11 +462,12 @@
   const calendarQuery = request.calendarQuery
     ? normalizeCalendarQuery(request.calendarQuery)
     : null;
-  const promises = {};
-  if (calendarQuery) {
-    promises.verifyCalendarQueryThreadIDs =
-      verifyCalendarQueryThreadIDs(calendarQuery);
-  }
+  const verifyCalendarQueryThreadIDsPromise = (async () => {
+    if (calendarQuery) {
+      await verifyCalendarQueryThreadIDs(calendarQuery);
+    }
+  })();
+
   const username = request.username ?? request.usernameOrEmail;
   if (!username) {
     if (hasMinCodeVersion(viewer.platformDetails, { native: 150 })) {
@@ -473,10 +481,11 @@
     FROM users
     WHERE LCASE(username) = LCASE(${username})
   `;
-  promises.userQuery = dbQuery(userQuery);
-  const {
-    userQuery: [userResult],
-  } = await promiseAll(promises);
+  const userQueryPromise = dbQuery(userQuery);
+  const [[userResult]] = await Promise.all([
+    userQueryPromise,
+    verifyCalendarQueryThreadIDsPromise,
+  ]);
 
   if (userResult.length === 0) {
     if (hasMinCodeVersion(viewer.platformDetails, { native: 150 })) {
diff --git a/keyserver/src/session/cookies.js b/keyserver/src/session/cookies.js
--- a/keyserver/src/session/cookies.js
+++ b/keyserver/src/session/cookies.js
@@ -29,7 +29,6 @@
 import type { UserInfo } from 'lib/types/user-types.js';
 import { isDev } from 'lib/utils/dev-utils.js';
 import { values } from 'lib/utils/objects.js';
-import { promiseAll } from 'lib/utils/promises.js';
 
 import {
   isBcryptHash,
@@ -478,26 +477,34 @@
     return result.viewer;
   }
 
-  const promises = {};
-  if (result.cookieSource === cookieSources.BODY) {
-    // We initialize a socket's Viewer after the WebSocket handshake, since to
-    // properly initialize the Viewer we need a bunch of data, but that data
-    // can't be sent until after the handshake. Consequently, by the time we
-    // know that a cookie may be invalid, we are no longer communicating via
-    // HTTP, and have no way to set a new cookie for HEADER (web) clients.
-    const platformDetails =
-      result.type === 'invalidated' ? result.platformDetails : null;
-    const deviceToken =
-      result.type === 'invalidated' ? result.deviceToken : null;
-    promises.anonymousViewerData = createNewAnonymousCookie({
-      platformDetails,
-      deviceToken,
-    });
-  }
-  if (result.type === 'invalidated') {
-    promises.deleteCookie = deleteCookie(result.cookieID);
-  }
-  const { anonymousViewerData } = await promiseAll(promises);
+  const anonymousViewerDataPromise: Promise<?AnonymousViewerData> =
+    (async () => {
+      if (result.cookieSource !== cookieSources.BODY) {
+        return undefined;
+      }
+      // We initialize a socket's Viewer after the WebSocket handshake, since to
+      // properly initialize the Viewer we need a bunch of data, but that data
+      // can't be sent until after the handshake. Consequently, by the time we
+      // know that a cookie may be invalid, we are no longer communicating via
+      // HTTP, and have no way to set a new cookie for HEADER (web) clients.
+      const platformDetails =
+        result.type === 'invalidated' ? result.platformDetails : null;
+      const deviceToken =
+        result.type === 'invalidated' ? result.deviceToken : null;
+      return await createNewAnonymousCookie({
+        platformDetails,
+        deviceToken,
+      });
+    })();
+  const deleteCookiePromise = (async () => {
+    if (result.type === 'invalidated') {
+      await deleteCookie(result.cookieID);
+    }
+  })();
+  const [anonymousViewerData] = await Promise.all([
+    anonymousViewerDataPromise,
+    deleteCookiePromise,
+  ]);
 
   if (!anonymousViewerData) {
     return null;
@@ -520,9 +527,15 @@
   }
   const deviceToken = result.type === 'invalidated' ? result.deviceToken : null;
 
+  const deleteCookiePromise = (async () => {
+    if (result.type === 'invalidated') {
+      await deleteCookie(result.cookieID);
+    }
+  })();
+
   const [anonymousViewerData] = await Promise.all([
     createNewAnonymousCookie({ platformDetails, deviceToken }),
-    result.type === 'invalidated' ? deleteCookie(result.cookieID) : null,
+    deleteCookiePromise,
   ]);
 
   return createViewerForInvalidFetchViewerResult(result, anonymousViewerData);
diff --git a/keyserver/src/socket/socket.js b/keyserver/src/socket/socket.js
--- a/keyserver/src/socket/socket.js
+++ b/keyserver/src/socket/socket.js
@@ -81,7 +81,7 @@
   isCookieMissingSignedIdentityKeysBlob,
   isCookieMissingOlmNotificationsSession,
 } from '../session/cookies.js';
-import { Viewer } from '../session/viewer.js';
+import { Viewer, type AnonymousViewerData } from '../session/viewer.js';
 import { serverStateSyncSpecs } from '../shared/state-sync/state-sync-specs.js';
 import { commitSessionUpdate } from '../updaters/session-updaters.js';
 import { compressMessage } from '../utils/compress.js';
@@ -313,15 +313,21 @@
       } else if (error.message === 'client_version_unsupported') {
         const { viewer } = this;
         invariant(viewer, 'should be set');
-        const promises = {};
-        promises.deleteCookie = deleteCookie(viewer.cookieID);
-        if (viewer.cookieSource !== cookieSources.BODY) {
-          promises.anonymousViewerData = createNewAnonymousCookie({
-            platformDetails: error.platformDetails,
-            deviceToken: viewer.deviceToken,
-          });
-        }
-        const { anonymousViewerData } = await promiseAll(promises);
+        const deleteCookiePromise = deleteCookie(viewer.cookieID);
+        const anonymousViewerDataPromise: Promise<?AnonymousViewerData> =
+          (async () => {
+            if (viewer.cookieSource === cookieSources.BODY) {
+              return undefined;
+            }
+            return await createNewAnonymousCookie({
+              platformDetails: error.platformDetails,
+              deviceToken: viewer.deviceToken,
+            });
+          })();
+        const [anonymousViewerData] = await Promise.all([
+          anonymousViewerDataPromise,
+          deleteCookiePromise,
+        ]);
         let authErrorMessage: AuthErrorServerSocketMessage = {
           type: serverSocketMessageTypes.AUTH_ERROR,
           responseTo,
@@ -441,7 +447,7 @@
   async handleClientSocketMessage(
     message: ClientSocketMessage,
   ): Promise<ServerServerSocketMessage[]> {
-    const resultPromise = (async () => {
+    const resultPromise: Promise<ServerServerSocketMessage[]> = (async () => {
       if (message.type === clientSocketMessageTypes.INITIAL) {
         this.markActivityOccurred();
         return await this.handleInitialClientSocketMessage(message);
@@ -459,7 +465,7 @@
       }
       return [];
     })();
-    const timeoutPromise = (async () => {
+    const timeoutPromise: Promise<empty> = (async () => {
       await sleep(serverResponseTimeout);
       throw new ServerError('socket_response_timeout');
     })();
@@ -568,18 +574,19 @@
       const { sessionUpdate, deltaEntryInfoResult } =
         sessionInitializationResult;
 
-      const promises = {};
-      promises.deleteExpiredUpdates = deleteUpdatesBeforeTimeTargetingSession(
-        viewer,
-        oldUpdatesCurrentAsOf,
-      );
-      promises.fetchUpdateResult = fetchUpdateInfos(
+      const deleteExpiredUpdatesPromise =
+        deleteUpdatesBeforeTimeTargetingSession(viewer, oldUpdatesCurrentAsOf);
+      const fetchUpdateResultPromise = fetchUpdateInfos(
         viewer,
         oldUpdatesCurrentAsOf,
         calendarQuery,
       );
-      promises.sessionUpdate = commitSessionUpdate(viewer, sessionUpdate);
-      const { fetchUpdateResult } = await promiseAll(promises);
+      const sessionUpdatePromise = commitSessionUpdate(viewer, sessionUpdate);
+      const [fetchUpdateResult] = await Promise.all([
+        fetchUpdateResultPromise,
+        deleteExpiredUpdatesPromise,
+        sessionUpdatePromise,
+      ]);
 
       const { updateInfos, userInfos } = fetchUpdateResult;
       const newUpdatesCurrentAsOf = mostRecentUpdateTimestamp(
diff --git a/keyserver/src/updaters/thread-permission-updaters.js b/keyserver/src/updaters/thread-permission-updaters.js
--- a/keyserver/src/updaters/thread-permission-updaters.js
+++ b/keyserver/src/updaters/thread-permission-updaters.js
@@ -121,6 +121,19 @@
     INNER JOIN memberships cm ON cm.thread = t.containing_thread_id
     WHERE t.id = ${threadID} AND cm.user IN (${userIDs})
   `;
+  const containingMembershipPromise: Promise<
+    $ReadOnlyArray<{
+      +user: number,
+      +containing_role: number,
+    }>,
+  > = (async () => {
+    if (intent === 'leave') {
+      // Membership in the container only needs to be checked for members
+      return [];
+    }
+    const [result] = await dbQuery(containingMembershipQuery);
+    return result;
+  })();
   const [
     [membershipResults],
     [parentMembershipResults],
@@ -129,14 +142,7 @@
   ] = await Promise.all([
     dbQuery(membershipQuery),
     dbQuery(parentMembershipQuery),
-    (async () => {
-      if (intent === 'leave') {
-        // Membership in the container only needs to be checked for members
-        return [];
-      }
-      const [result] = await dbQuery(containingMembershipQuery);
-      return result;
-    })(),
+    containingMembershipPromise,
     changeRoleThreadQuery(threadID, role),
   ]);
 
diff --git a/keyserver/src/updaters/thread-updaters.js b/keyserver/src/updaters/thread-updaters.js
--- a/keyserver/src/updaters/thread-updaters.js
+++ b/keyserver/src/updaters/thread-updaters.js
@@ -39,6 +39,7 @@
   changeRole,
   recalculateThreadPermissions,
   commitMembershipChangeset,
+  type MembershipChangeset,
   type MembershipRow,
 } from './thread-permission-updaters.js';
 import createMessages from '../creators/message-creator.js';
@@ -341,7 +342,6 @@
   const silenceMessages = options?.silenceMessages ?? false;
   const ignorePermissions =
     (options?.ignorePermissions && viewer.isScriptViewer) ?? false;
-  const validationPromises = {};
 
   const changedFields: { [string]: string | number } = {};
   const sqlUpdate: { [string]: ?string | number } = {};
@@ -352,12 +352,12 @@
       throw new ServerError('invalid_chat_name');
     }
     changedFields.name = name;
-    sqlUpdate.name = name ?? null;
+    sqlUpdate.name = name;
   }
   const { description } = request.changes;
   if (description !== undefined && description !== null) {
     changedFields.description = description;
-    sqlUpdate.description = description ?? null;
+    sqlUpdate.description;
   }
   if (request.changes.color) {
     const color = request.changes.color.toLowerCase();
@@ -406,11 +406,11 @@
     throw new ServerError('invalid_parameters');
   }
 
-  validationPromises.serverThreadInfos = fetchServerThreadInfos({
+  const serverThreadInfosPromise = fetchServerThreadInfos({
     threadID: request.threadID,
   });
 
-  validationPromises.hasNecessaryPermissions = (async () => {
+  const hasNecessaryPermissionsPromise = (async () => {
     if (ignorePermissions) {
       return;
     }
@@ -461,7 +461,10 @@
     }
   })();
 
-  const { serverThreadInfos } = await promiseAll(validationPromises);
+  const [serverThreadInfos] = await Promise.all([
+    serverThreadInfosPromise,
+    hasNecessaryPermissionsPromise,
+  ]);
 
   const serverThreadInfo = serverThreadInfos.threadInfos[request.threadID];
   if (!serverThreadInfo) {
@@ -701,30 +704,35 @@
     }
   })();
 
-  const intermediatePromises = {};
-  intermediatePromises.updateQuery = updateQueryPromise;
-  intermediatePromises.updateRoles = updateRolesPromise;
-
-  if (newMemberIDs) {
-    intermediatePromises.addMembersChangeset = (async () => {
+  const addMembersChangesetPromise: Promise<?MembershipChangeset> =
+    (async () => {
+      if (!newMemberIDs) {
+        return undefined;
+      }
       await Promise.all([updateQueryPromise, updateRolesPromise]);
       return await changeRole(request.threadID, newMemberIDs, null, {
         setNewMembersToUnread: true,
       });
     })();
-  }
 
-  const threadRootChanged =
-    rolesNeedUpdate || nextParentThreadID !== oldParentThreadID;
-  if (threadRootChanged) {
-    intermediatePromises.recalculatePermissionsChangeset = (async () => {
+  const recalculatePermissionsChangesetPromise: Promise<?MembershipChangeset> =
+    (async () => {
+      const threadRootChanged =
+        rolesNeedUpdate || nextParentThreadID !== oldParentThreadID;
+      if (!threadRootChanged) {
+        return undefined;
+      }
       await Promise.all([updateQueryPromise, updateRolesPromise]);
       return await recalculateThreadPermissions(request.threadID);
     })();
-  }
 
-  const { addMembersChangeset, recalculatePermissionsChangeset } =
-    await promiseAll(intermediatePromises);
+  const [addMembersChangeset, recalculatePermissionsChangeset] =
+    await Promise.all([
+      addMembersChangesetPromise,
+      recalculatePermissionsChangesetPromise,
+      updateQueryPromise,
+      updateRolesPromise,
+    ]);
 
   const membershipRows: Array<MembershipRow> = [];
   const relationshipChangeset = new RelationshipChangeset();