Is there any way of disable any kind of notification on the system and keep only the in-app bubbles with the numbers?

Sometimes I get several messages and my event screen gets filled with messages (I mean, 30+ notifications). Usually, wazapp freezes when this happens and the cell phone start to run really slowly (I believe that is happening because of the memory usage increase for each notification)

I unchecked the box for system notification and disabled the sound and vibration but I'm still getting system notification on the top bar and the event screen.