I tried the steps above and I notice that at
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Open the VFB
Try and delete Curves from the Edit Tone Mapping window
This is where mine slows down and I get major right-click lag.
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the right click was instant and not laggy, but choosing delete took about 2 or 3 seconds for Curves to disappear - before that point, the "+, Reset, Presets" disappeared and Curves still seemed to be there, until finally things redrew and Curves vanished and the buttons came back. Once that has happened, the same thing happens whenever deleting the bottom operator in the stack (and does not happen if I restart Max and delete the bottom operator in the stack without adding Curves; also does not happen if I add other operators rather than Curves to the bottom of the stack and then delete those).
Is this what you are experiencing?
Video attached, showing first deleting before curves working smooththly, then addition and deletion of Filmic working smoothly, then Curves after which things get a bit strange :)
EDIT - just to confirm, once Curves is added, deleting ANY operator in the stack (not just Curves, and not just the bottom one) causes this redraw lag for the delete to take effect in a redraw.
Also, I notice that once Curves is added, when you click and drag to reposition an item in the stack, the blue line no longer shows up to show where the item will be dropped (but it still drops just fine with no lag).