Firstly I will try to explain how the setup I am trying to debug works.

• First off, an XHR/Ajax request is made from the client (JavaScript).
• This request gets sent off to a Windows/Apache/PHP server
• This server acts as a proxy, which accepts the request, processes the data and proxies it onto another server, with cURL
• The cURL request is sent to a Windows IIS server, which accepts the data, and returns some values back to the PHP proxy server
• The PHP proxy server does some work with the values and then returns them back to the client (JavaScript)

Some other information:

• The purpose of this PHP cURL proxy is that it is a single sign-on authentication API.
• The process is much inspired by this answer: How youtube gets logged in to gmail account without redirect?.
• The PHP cURL proxy acts as the single sign-on API which stores authentication tokens.
• The Windows IIS server is the place that username/passwords are sent to, and potentially returns an auth token.

The problem:

On the initial request, there is a 30 second wait time until a response is returned, it's almost like the servers are asleep and need waking up. After the initial request successfully gets a response, subsequent requests are returned in less than 1 second. If no requests are made for a space of time (say 30 minutes), the slow initial request happens again.

A direct request to the PHP Auth API never has this long wait, the same goes for the Windows IIS endpoint - but when there's a cURL between the two, the long wait occurs.

Can anyone point me in the right direction here? Maybe it's something obvious that I haven't considered? Would "Keep connection alive" type parameters be of help?

I hope I have explained the problem properly and if more information is needed, just ask.

Thank you Stack Overflow!