...

CONFIG proxy.config.task_threads INT 4

Step 3 – Secure

Maximum Inbound Concurrent Connections

The default config for ATS specifies that this server can handle up to 30,000 connections.
For my purposes, that's a bit excessive. I figure with 1,024 connections there's plenty
of "elbow room".

CONFIG proxy.config.net.connections_throttle INT 1K

That's it. Go ahead and refresh your cache(if necessary), restart ATS, and enjoy your tuned proxy server.