Obviously I don't know what you'd use on a CNC (yet) but if you were routing by hand with a 6mm bit you'd use the fastest router speed (24,000 rpm usually) and take 4mm deep cuts max. Feed can be anything fastest enough to prevent the bit from burning the timber. By hand and with a jig I'd guess I'd be doing about 2.5m/min but it's mostly done by ear. If you can use a 1/2" straight bit you can go much much faster they are nearly indestructible in wood.