While the default configuration values for ATS will get you up and running,
at the moment they're somewhat designed for regression testing and not real-world applications.

...

• Make/Model: Apple iMac Mid 2011
• CPU: 3.4 Ghz Intel Core i7 (quad-core w/Hyperthreading)
• Memory: 8GB
• Disk: 1TB
• OS: Mac OS X v10.89.51
• Cache Size: 32GB24GB

Current Testing Regimen

The following settings have been tested against the following:

...

CONFIG proxy.config.http.background_fill_completed_threshold FLOAT 0.000000

HTTP Cache Options

The default config for ATS specifies that headers for "No-Cache" from the client be ignored, and that those from a server be honored.

I actually prefer the reverse to be true, hoping that the browser knows when bypassing the cache would be useful.

CONFIG proxy.config.http.cache.ignore_client_no_cache INT 0
CONFIG proxy.config.http.cache.ims_on_client_no_cache INT 0
CONFIG proxy.config.http.cache.ignore_server_no_cache INT 1

HTTP Cache Options

The default config for ATS specifies that after 1 day(86,400 seconds), any object without a specific expiration
cannot be cached. I'd prefer that they stick around for between 1-3 months. This setting is contentious in that what it should be is debatable.

...