The sliding is indeed a problem.

Take a simple animation.
Start from Zero pose at frame 1, and lower the arms to the hip at at frame 30.
Run the animation, and you see??

In the first frames the arms go UP, before starting to go down.
And that is just one joint.

Turn the head left at frame 30
And the head will turn to the right before turning to the left .

Poser main group is the hip.

To get to the feet, you cross mulitple joints, that all do the reverse before going the "wanted" way.
This in great part creates the sliding of the feet.

Other problem.
Start with a figure at 85%
Set frame 10 of a 30 frame animations at figure = 100%

Check frame 13 and you will see your figure at 105% before coming back tot 100% at frame 30.

In turning and bending bodyparts of a normal figure this gives some very realistic views.

For "HARD" moves, as feet on the floor that may NOT slide, it can be a nightmare.
You have to go in the "graph" mode, change the Interpollation mode.
Page 340 in the PoserPro2010 manual.

Hope this helps a bit.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!