implement ornicar's suggestions.

app/controllers/LilaController.scala

@@ -305,7 +305,7 @@ private[controllers] trait LilaController
           import makeTimeout.short
           (Env.hub.actor.relation ? GetOnlineFriends(me.id) map {
             case OnlineFriends(users, usersPlaying) => (users, usersPlaying)
-          } recover { case _ => (Nil,Nil) }) zip
+          } recover { case _ => (Nil,Set.empty[String]) }) zip
             Env.team.api.nbRequests(me.id) zip
             Env.challenge.api.countInFor(me.id) zip
             Env.notifyModule.api.unreadCount(Notifies(me.id)).map(_.value)

app/views/base/layout.scala.html

@@ -169,7 +169,8 @@ withLangAnnotations: Boolean = true)(body: Html)(implicit ctx: Context)
       </div>
     </div>
     @ctx.me.map { me =>
-    <div id="friend_box" data-preload="@ctx.friends.map(_.titleName).mkString(",")" data-playing="@ctx.friendsPlaying.map(_.titleName).mkString(",")" >
+    <div id="friend_box" data-preload="@ctx.friends.map(_.titleName).mkString(",")"
+                         data-playing="@ctx.friendsPlaying.mkString(",")" >
       <div class="title"><strong class="online"> </strong> @trans.onlineFriends()</div>
       <div class="content_wrap">
         <div class="content list"></div>

modules/api/src/main/Context.scala

@@ -8,7 +8,7 @@ import lila.user.{ UserContext, HeaderUserContext, BodyUserContext }
 
 case class PageData(
   friends: List[lila.common.LightUser],
-  friendsPlaying: List[lila.common.LightUser],
+  friendsPlaying: Set[String],
   teamNbRequests: Int,
   nbChallenges: Int,
   nbNotifications: Int,
@@ -18,7 +18,7 @@ case class PageData(
 
 object PageData {
 
-  val default = PageData(Nil, Nil, 0, 0, 0, Pref.default, false, false)
+  val default = PageData(Nil, Set.empty, 0, 0, 0, Pref.default, false, false)
 
   def anon(blindMode: Boolean) = default.copy(blindMode = blindMode)
 }

modules/hub/src/main/actorApi.scala

@@ -185,7 +185,7 @@ case class Remove(gameId: String)
 package relation {
 case class ReloadOnlineFriends(userId: String)
 case class GetOnlineFriends(userId: String)
-case class OnlineFriends(users: List[LightUser], usersPlaying: List[LightUser])
+case class OnlineFriends(users: List[LightUser], usersPlaying: Set[String])
 case class Block(u1: String, u2: String)
 case class UnBlock(u1: String, u2: String)
 }

modules/relation/src/main/RelationActor.scala

@@ -21,7 +21,7 @@ private[relation] final class RelationActor(
 
   private var onlines = Map[ID, LightUser]()
 
-  private var onlinePlayings = Map[ID, LightUser]()
+  private var onlinePlayings = Set[ID]()
 
   override def preStart(): Unit = {
     context.system.lilaBus.subscribe(self, 'startGame)
@@ -41,7 +41,7 @@ private[relation] final class RelationActor(
     case ReloadOnlineFriends(userId) => onlineFriends(userId) foreach {
       case OnlineFriends(users, friendsPlaying) =>
         bus.publish(SendTo(userId, "following_onlines", users.map(_.titleName)), 'users)
-        bus.publish(SendTo(userId, "following_playings", friendsPlaying.map(_.titleName)), 'users)
+        bus.publish(SendTo(userId, "following_playings", friendsPlaying), 'users)
     }
 
     case NotifyMovement =>
@@ -62,7 +62,7 @@ private[relation] final class RelationActor(
 
     case msg: lila.game.actorApi.StartGame =>
       val usersPlaying = getGameUsers(msg.game)
-      onlinePlayings = onlinePlayings ++ usersPlaying.map(u => u.id -> u)
+      onlinePlayings = onlinePlayings ++ usersPlaying.map(_.id)
       notifyFollowers(usersPlaying, "following_playing")
   }
 
@@ -80,8 +80,8 @@ private[relation] final class RelationActor(
       OnlineFriends(friends, friendsPlaying)
     }
 
-  private def getFriendsPlaying(friends: List[LightUser]): List[LightUser] = {
-    friends.filter(p => onlinePlayings.contains(p.id))
+  private def getFriendsPlaying(friends: List[LightUser]): Set[String] = {
+    friends.filter(p => onlinePlayings.contains(p.id)).map(_.id).toSet
   }
 
   private def notifyFollowers(users: List[LightUser], message: String) {

public/javascripts/main.js

@@ -1154,12 +1154,17 @@ lichess.notifyApp = (function() {
     },
     _setPlaying: function(userName, playing) {
 
-        var user = this.users.find(function(u) {
-            return u.name === userName;
+        var isSameUser = function(userName, user) {
+           var id = $.fp.contains(user.name, ' ') ? user.name.split(' ')[1] : user.name;
+           return id === userName;
+        }
+
+        var user = this.users.filter(function(u) {
+            return isSameUser(userName, u);
         });
 
-        if (user) {
-            user["playing"] = playing;
+        if (user.length > 0) {
+            user[0]["playing"] = playing;
         }
 
     },