The out-of-process search indexing feature improves save record performance by performing all required search reindexing in a separate non-interactive request. PHP doesn't have any standard notion of multiprocessing, so we have jerryrigged system that initiates a separate web request to handle indexing. Indexing is triggered by an internal socket connection to the web server that sends a minimal HTTP request.
When using https with some server/network configurations it may not be possible to validate the ssl certificate when connecting internally to trigger indexing. Often adding server-side CA certs will solve the problem but this may not be practical (Ex. you don't have enough access on the machine to add CA certs).
We need an option to disable certificate checks here as a last resort. While disabling certificate checks is never a great idea no data is transferred over the connection used to trigger indexing so this shouldn't be a glaring security hole. Having the option available will be very helpful in some situations.