I think a simple solution would be: use a Fixed Node Tree and just make one of the nodes NR. Then if you're experiencing slow-downs, select the node, bypass it, then select all the nodes in the timeline and use Color -> Ripple Node Changes to Selected Clips. In this case, you'd only ripple the changes to #7, the "Noise Red" node. Here's a node tree where that would work:

Of course, you could use a much more complex node structure, even 30-40-50 nodes if you wanted. This will give you the functionality you're looking for without a lot of trouble.