Pause after a node in preview or pause selected

When you need to tweak a node in the beginning  or middle of node flow it's sometimes super slow and unresponsive  because Substance Designer   calculates evrything  after.  Diconnecting  and re-connecting  works but it makes so much exra troubles.

I'd love  to see an option to pause evrything but only after a node in 2d preview currently  with some  "paused" indication  in 3d preview .    In fact I think it should be a default behavior.