graph editor, elastic time control - instant slomo / speedup

If one makes larger projects width blender, there come times in your animation that the speed of it all might not look equal, or there may be 'action - dead' periods in your movie. Also sometimes you animated correctly but its to fast or its to slow. Or later you want some scenes to speed up a bit or slow down a bit in the near end production.

Well for a few objects, the graph editor works nicely to correct this Also, we can drag the dope sheet events.

However if we would like to aply changes smoothly over parts of a whole animation, a 3rd kind of editing besides graph/dope events would be great, that not relates to events already in the dope sheet/graph editor. Instead, it should act as an overlay providing control over time speed itself (allow for instant slomo effects as well)

The easiest way to achieve this would be: A master modifier for the graph editor that applies to all channels
Based upon a curve, it should recalculate every graph-editor curve below it.

• it would mean that curves already be defined in the graph editor, could undergo effects of another curve ea 2 curves width different offsets acting upon the speed of the animation.

• the dope sheet comes perhaps close to this currently but doing a slomo or slight speedup of certain parts of a animation is not really practical if you got hundreds of objects to work width.