What is the optimal Bitcoin Core 0.17 settings in bitcoin.conf settings for running a full node with a very beefy system?
dbcache is the only significant performance influencing option.  Performance may be improved somewhat by increasing receive and send buffer sizes.

You don't specify exactly what application's you're concerned with speeding up.  To lower block reception latency you could connect to matt's public fibre network. See http://bitcoinfibre.org/public-network.html