Inline RoomBuffer::id to avoid cloning Arcs all the time

It accounts for half the CPU time in release mode

src/buffers/room.rs

@@ -588,6 +588,7 @@ impl Buffer for RoomBuffer {
       })
   }
 
+  #[inline]
   fn id(&self) -> BufferId {
     BufferId::Room(self.room_id.clone())
   }