The function seilentMoveTo is defined like this:
FP.silentMoveTo = function(sectionAnchor, slideAnchor){
FP.setScrollingSpeed (0, 'internal');
FP.moveTo(sectionAnchor, slideAnchor)
FP.setScrollingSpeed (originals.scrollingSpeed, 'internal');
};
But as FP.moveTo calls to scrollPage which has a call to requestAnimFrame and it is asynchronous, the scrollingSpeed is reseted to its original value (700) and the movement is done WITH animation.
The solution would be to define the function moveTo with a third argument: callback and pass this callback to the function scrollPage, which accepts a callback as the second argument of the function.
Inside the callback would be the call to FP.setScrollingSpeed (originals.scrollingSpeed, 'internal');