Until now, in order to verify your firewall supports the numbers described in its data sheet (connections per second, latency and more), you needed to invest lots of $$$ in expensive proprietary testing gear.
This is not the case any more!!!
No matter if you are a customer, QA engineer or developer, you can now easily do all these tests using the TRex tool.
At a fraction of the hardware cost, and with the software free, you can now test full 40G (100G under development, will be available soon) line rate of TCP connections.
TRex can simulate hundreds of thousands connections per second, and it also supports NAT and TCP sequence number randomization in client->server and server->client directions.
Check out the TRex Documentation to see what else it can do for you.
For ASA testing details look here: