Apache Reference: mod_proxy, ProxyReceiveBufferSize
Explicit Network Buffer Size for Outgoing Proxy Connections
Syntax: ProxyReceiveBufferSize A
Example: ProxyReceiveBufferSize 2048
Since: Apache 1.3
This directive specifies an explicit network buffer size for outgoing HTTP, HTTPS, and FTP connections, so as to increase throughput. The buffer size must be greater than 512 or set to 0 to indicate that the operating system's default buffer size should be used.