title: FCM display messages sometimes very slow
body: <p>I am sending display messages to FCM using this request:</p>
  
  <pre><code>curl -i -H 'Content-type: application/json' -H 'Authorization: ****' -XPOST https://fcm.googleapis.com/fcm/send -d '{"time_to_live":120,"priority":"high","content_available":true,"condition":"'\''4pz87gsel7183b7kcadw1dwzv'\'' in topics OR '\''4njsfszcgd9m765d6suktsz2a'\'' in topics OR '\''match-4i5yvb5co56meztqpc1quflk9'\'' in topics","data":{"event_id":"4i5yvb5co56meztqpc1quflk9_20180715150017","timestamp":1531666817},"notification":{"title":"test123,"body":"\u231a test123","sound":"sound","click_action":"my_action_link","android_channel_id":"ticker"}}'
  </code></pre>
  
  <p>But sometimes this message takes up to 10 minutes to get delivered to the clients? (for iOS and android). How can i achieve a faster delivery?</p>