diff --git a/store/sqlstore/post_store.go b/store/sqlstore/post_store.go
index cafca3d666..0364ca3802 100644
--- a/store/sqlstore/post_store.go
+++ b/store/sqlstore/post_store.go
@@ -819,33 +819,31 @@ func (s *SqlPostStore) prepareThreadedResponse(posts []*postWithExtra, extended,
 			}
 		}
 	}
-	var users []*model.User
+	// usersMap is the global profile map of all participants from all threads.
+	usersMap := make(map[string]*model.User, len(userIds))
 	if extended {
-		var err error
-		users, err = s.User().GetProfileByIds(context.Background(), userIds, &store.UserGetByIdsOpts{}, true)
+		users, err := s.User().GetProfileByIds(context.Background(), userIds, &store.UserGetByIdsOpts{}, true)
 		if err != nil {
 			return nil, err
 		}
+		for _, user := range users {
+			usersMap[user.Id] = user
+		}
 	} else {
 		for _, userId := range userIds {
-			users = append(users, &model.User{Id: userId})
+			usersMap[userId] = &model.User{Id: userId}
 		}
 	}
+
 	processPost := func(p *postWithExtra) error {
 		p.Post.ReplyCount = p.ThreadReplyCount
 		if p.IsFollowing != nil {
 			p.Post.IsFollowing = model.NewBool(*p.IsFollowing)
 		}
-		for _, th := range p.ThreadParticipants {
-			var participant *model.User
-			for _, u := range users {
-				if u.Id == th {
-					participant = u
-					break
-				}
-			}
-			if participant == nil {
-				return errors.New("cannot find thread participant with id=" + th)
+		for _, userID := range p.ThreadParticipants {
+			participant, ok := usersMap[userID]
+			if !ok {
+				return errors.New("cannot find thread participant with id=" + userID)
 			}
 			p.Post.Participants = append(p.Post.Participants, participant)
 		}
diff --git a/store/sqlstore/thread_store.go b/store/sqlstore/thread_store.go
index 8a1cce8f20..9592a1eee9 100644
--- a/store/sqlstore/thread_store.go
+++ b/store/sqlstore/thread_store.go
@@ -291,7 +291,10 @@ func (s *SqlThreadStore) GetThreadsForUser(userId, teamId string, opts model.Get
 	}
 	totalUnreadThreads := totalUnreadThreadsResult.Data.(int64)
 
+	// userIds is the de-duped list of participant ids from all threads.
 	var userIds []string
+	// userIdMap is the map of participant ids from all threads.
+	// Used to generate userIds
 	userIdMap := map[string]bool{}
 
 	result := &model.Threads{
@@ -315,30 +318,30 @@ func (s *SqlThreadStore) GetThreadsForUser(userId, teamId string, opts model.Get
 				}
 			}
 		}
-		var users []*model.User
+		// usersMap is the global profile map of all participants from all threads.
+		usersMap := make(map[string]*model.User, len(userIds))
 		if opts.Extended {
-			var err error
-			users, err = s.User().GetProfileByIds(context.Background(), userIds, &store.UserGetByIdsOpts{}, true)
+			users, err := s.User().GetProfileByIds(context.Background(), userIds, &store.UserGetByIdsOpts{}, true)
 			if err != nil {
 				return nil, errors.Wrapf(err, "failed to get threads for user id=%s", userId)
 			}
+			for _, user := range users {
+				usersMap[user.Id] = user
+			}
 		} else {
 			for _, userId := range userIds {
-				users = append(users, &model.User{Id: userId})
+				usersMap[userId] = &model.User{Id: userId}
 			}
 		}
 
+		result.Threads = make([]*model.ThreadResponse, 0, len(threads))
 		for _, thread := range threads {
-			var participants []*model.User
+			participants := make([]*model.User, 0, len(thread.Participants))
+			// We get the user profiles for only a single thread filtered from the
+			// global users map.
 			for _, participantId := range thread.Participants {
-				var participant *model.User
-				for _, u := range users {
-					if u.Id == participantId {
-						participant = u
-						break
-					}
-				}
-				if participant == nil {
+				participant, ok := usersMap[participantId]
+				if !ok {
 					return nil, errors.New("cannot find thread participant with id=" + participantId)
 				}
 				participants = append(participants, participant)