10w socket connect linux net block how to Break through the bottleneck

I write a push server using nodejs, which can support 70w users long connect。

but when i enable the user heartbeat like this，

 var timeInterval = Math.floor(Math.random() * 1200000;
 setInterval(function()
      client.pingreq();
 },timeInterval);

there will be too many little packet that block the net and affect the message push.

and I use the iftop, check that, the net has low speed.

the top command shows the server has a lot of free memory and cpu to use.

does linux can config to change this problem?