why do you assume it is rpc?
theoretically, you could change the priority of the process. and run it in the background, rather than in a... terminal/CLI of some sort.
but since your miner, your operating system, your batch files, your bitcoin.conf, and everything else relevant to your question (except your actual GPU) is an unknown, it's hard to say.
win 7, rpcminer-cuda newest, running no flags other than login, not sure where bitcoin.conf would be, not sure what else is relevant