Couple of things comes to mind. First it seems like you're always creating the full resolution image. In the case of the low-res selection, you only see the lower res one, but in the comp you also create the full-res one anyways. This is one of the major differences between QC and Vuo. In QC you wouldn't have created the one that wasn't selected, as it pulls the values to the output. In Vuo however, it pushes all calculations to the conclusion from the inputs enabling background calculations, but at the price of having to be a bit more careful about the values and blocking events.
I also wonder how you deal with the wrap-mode in QC? I haven't used this (vuo) node myself, but if I understand it correctly, it in this instance would check 4 4k frames/textures at every frame cycle. That is a pretty hefty operation - especially for older/mac hw. I would try removing those nodes to check performance.
Vuo is pretty different at its core, using push instead of pull when it comes to the data flow. This might be the most important thing to grasp when switching. Getting out of the subcomp mentality is perhaps a bit challenging at first. Points and lists and the generation of these are also king when it comes to both create and manipulate stuff.
Are these pure copies of one main line, or should all the lines have different properties in addition to the basic rotation/translation?
You can use the combine nodes to create a collection of objects that you then can transform again via the transform nodes. Combining makes all the objects you combine children of the object so that the relation may seem clearer after spending some time with it. This can also be nested and/or copied with new transformations.
Replicate in Space
Here you can use the Copy 3D Object (TRS) in combination with Make Points Along Line (key ingredient) to easily replicate stuff however you'd like. If you right-click on the From/To ports you can reset to generic type, then change it to a 3D point to use less nodes. Make Points along Spline can also be used to create more complex patterns with a curved (or crazy) approach to the "replication" points.
Attaching a demo composition with a few ways to do stuff like this. You'll need my mm.points nodeset which is in the node gallery. Poke around and see if it makes sense!
I thought I had released a XYZ lerp thingy long time ago, but it seems that I haven't. If it's needed for V2 I'll probably include it then in the updated package (that probably will break old comps).
It won't blend/morph scenes, but it'll do the points at least. Singular nodes attached, but will probably not translate well into the future. Use at your own peril, and make a note of which comps you are using them with so that you can easily update it when/if necessary later.