I am trying to get a smooth scaling behaviour for a complex scene where the normal rendering just takes too long for a smooth scaling. I thus tried to use caching of nodes together with appropriate CacheHints. First of all I have a Group node which contains all other nodes that will be rendered. Caching is always switched on for this group node and the default setting for the CacheHint is QUALITY. Now my idea was to switch to SPEED before I start scaling the group node and back to QUALITY once I stop scaling (via mouse-wheel events). This works in principle and gives a better scaling behaviour than without it but I have observed the following strange behaviour. When I switch back from SPEED to QUALITY this does not force a rendering of the scene, which I think it should do because this is just like any other parameter change which would have a visible effect. On the other hand there is a noticable delay when switching initially from QUALITY to SPEED and it looks like this is causing a slow rendering, which in this case is not necessary because this transition cannot have any visible effect. This behaviour is strange because it is exactly the opposite of what I would expect and makes a smooth scaling impossible.