Walkabout in millimeter

Hi,
is there anyone here 've a problem with ‘walkabout mode’ in Rhino 8 (v.8.5)?
i use millimeter unit, and run so slow,
i already use WalkAbout, step size custom and change it into 1000 (assume it that walk step every 1 m), but nothing change…
do i miss something?
thanks 4 advance