It is also possible to have NSX alert you when DWF CPU and Heap utilization crosses a specific threshold as well as connections per second. By default, this is set to 100%, so if you do get any alerts, its already too late
To set the alerts, it needs to be done via the API, or via PowerNSX as shown in the example below:
PS /Users/dcoghlan> get-help Set-NsxFirewallThreshold -Examples
NAME
Set-NsxFirewallThreshold
SYNOPSIS
Sets the Distributed Firewall thresholds for CPU, Memory
and Connections per Second
-------------------------- EXAMPLE 1 --------------------------
PS />Set-NsxFirewallThreshold -Cpu 70 -Memory 70 -ConnectionsPerSecond 35000
CPU Memory ConnectionsPerSecond
--- ------ --------------------
cpu memory connectionsPerSecond