I'm running a PHP application (Moodle) under FastCGI in IIS 8.5, Windows Server 2012 R2 and PHP 5.4. There are two VM server nodes in the setup using an F5 load balancer. I am using Wincache for the File System and User caches and OPCache for the Opcode cache. The application writes to a MSSQL database using the Microsoft PHP SQLSRV drivers.
I'm trying to resolve some slow reponse issues we are getting when the site is busy. We get about 600 visitors per day.
One of the things that my research turned up is to set the responseBufferLimit setting to 0. But what isn't really explained anywhere is what the repercussions of doing that are.
Are there any reasons NOT to set it to 0? What are the consequences of setting it to 0?
If 0 isn't a good idea, how do I determine what the correct value should be?
(Yes, I am fully aware that 5.4 is an old version of PHP.)