I cut 18 mm Mdf in two passes with a 9.5mm cutter at 6m/min.

It should be possible to cut it in one pass but that depends on the size of the machine.

The higher the feed rates and the fewer passes you take the longer the tool will last, so if you are looking to run production pieces this is something you should look into.

Mdf is harsh on tooling it's massively abrasive and will wear out tools fast.