^^ I vote for ``Set the number of threads to service RPC calls (1-16, 0=auto, default: 0)`` and we should perhaps consider the same routine as you added for the -par switch then.

<pre>
// -rpcthreads=0 means autodetect, but nRPCThreads==0 means no concurrency
    nRPCThreads = GetArg("-rpcthreads", 0);
    if (nRPCThreads == 0)
        nRPCThreads = boost::thread::hardware_concurrency();
    if (nRPCThreads <= 1)
        nRPCThreads = 0;
    else if (nRPCThreads > MAX_RPC_THREADS)
        nRPCThreads = MAX_RPC_THREADS;
</pre>