This is what I have:
Feed and Depth of cut rates depend greatly on size of bit, material, and RPM of your spindle.
My wasteboard had a serious “bowl” to it, so I had to cut almost 1/8″ (~3mm) off it, and I was doing it at something like 7 passes with a rate of 30 inches/min. I’m using a Chinese spindle that came with my machine. If I had something like a Dewalt 611 (660? I forget which one is “popular” now) ….I’ve seen people chewing through MDF at well over 90 inches/min with something that powerful.
But really, if it’s already mostly flat, chances are you have to take off less than 1mm total, and could do that in 1-2 passes if you’re using a decent router as the spindle.