One can override this value via the sampleDensityWhenMoving="value" property in the volume tag, i.e.
<volume sampleDensityWhenMoving="0.01">CardiacCT</volume>
To switch the feature off set the value to 0, i.e.
<volume sampleDensityWhenMoving="0">CardiacCT</volume>
dragger="box" or dragger="trackball"
and
technique="light" or technique="isosurface" or technique="iso" or technique="mip"
and
tf="transferfunctionfile.tf"
i.e.
<volume dragger="box">CardiacCT</volume>
<volume tf="colour.tf">CardiacCT</volume>
<volume technique="isosurface">CardiacCT</volume>