1.3mm pass depth with a compression bit seems to be a pointless use of the tool as it will be acting as an upcut only. It also looks like an ambitious feed rate for a fairly tiny spindle-the fact that it comes as standard with a 1/8" collet is a clue that you can't expect too much from it.Have you tried a smaller bit,perhaps a straight 4mm,so the motor doesn't have to work as hard?