Push it to 24kRPm and 2000mm/min, Do NOt BE SHY. Use carbide only, whats that with the HSS??? I use HSS for foam only. Or rarely for deep reach somewhere when i dont want to spend on expensive tool. When profiling the profile needs to consist of 2 passes at say 10mm wide/ if tool is 6mm, as there must be a place for the chips to evacuate

This is how it should look when is cutting well, just adjust accordingly depth to your machine rigidity.