This option is used to enable buffering/compression of HTML output if the user's browser supports it. Default value is ON. This option will be ignored in the following scenarios:
php.ini has zlib.output_compression enabled.
php.ini has output_handler set to a handler.
zlib extension is not enabled. The Windows version of PHP has built-in support for this extension.
$g_use_persistent_connections
Use persistent database connections, setting this to ON will open the database once per connection, rather than once per page. There might be some scalability issues here and that is why it is defaulted to OFF.
