Performance issues selecting node graph

[wade-cheng]

Processing new selections for the node graph is slow [1], even though processing new selections for the artboard is fast [2]. Notice how for both, wiggling the selection around without getting new selections is fast. Perf only diverges when we actually select or deselect something.

[1]

selections_in_node_graph_slow.mp4

[2]

selections_in_artboard_fast.mp4

Discovered this while working on #2532 and #3290. This issue touches the same regions of code.

[TrueDoctor]

This is unfortunately currently somewhat expected as far as I can tell, the issue is not really the selection itself, but rather the rendering of the visual changes in the node graph. There is work going on to improve the rendering performance, but until then this is something we will have to live with