PHP Defaults required for Demo Framework

The Demo Framework is an install profile that uses the Features module extensively. This can be very expensive to your system resources during the installation of the actual DF profile as well as during the enablement of a Demo Framework Scenario. As it stands, the following settings are recommended for your php.ini configuration.

Max Execution Time
max_execution_time = 300
The setting of 300 is default for Acquia Dev Desktop. This setting has also been tested against PHP running on OSX/Homebrew. Acquia Cloud Free Tier environments also default to this setting.

Max Input Time
max_input_time = 120
The setting of 120 is default for Acquia Dev Desktop. This setting has also been tested against PHP running on OSX/Homebrew. Acquia Cloud Free Tier environments also default to this setting.

PHP Memory Limit
memory_limit = 256M
We have seen various results here. Acquia Cloud Free Tier environments have shown to be able to handle DF with as low as 128 MB though this is not consistent. OSX/Homebrew in specific configurations has required up to 1024 MB on some machines, which seems excessive. As of this writing, Acquia Dev Desktop defaults to 256 MB and this SHOULD be sufficient but you may want to dial it up to 512 MB just to be safe.

PHP Version
5.4 or higher
Some code used in DF uses Xautoload, which requires PSR-0 compliant class loading. You may be able to get away with 5.3 in some cases but it's not recommended. 5.4 or 5.5 are strongly recommended. On all versions of Acquia Cloud, you can change the PHP version for a specific environment through UI based configuration. See Configuring PHP settings on docs.acquia.com.

APC Settings
This is an oft-debated thing and varies per environment. The default APC configuration for Acquia Dev Desktop and Acquia Cloud Free Tier are good references for how to configure these settings. APC is not required but having it enabled should help improve performance and allow you to run Demo Framework with a lower default memory_limit.