When using a router it involves two speeds,
1) the speed the bit is spinning,
2) the speed at which the material is being fed.
The feed speed should never be greater than the ability of the bit to clear the material being removed.
A good feed speed will produce shavings, too fast does not allow the bit to cut properly and may cause chatter because the chips are not removed properly. Too slow may cause the wood to burn.
Common Router Speeds
1” Diameter Cutter – 24,000 RPM
1 1/4” – 2” Diameter Cutter – 18,000 RPM
2 1/4" - 2 1/2” Diameter Cutter – 16,000 RPM
3” – 3 1/2” Diameter Cutter – 12,000 RPM