First of all; thanks a lot for some really great KSP mods, and also for caring about improving game performance.
However, from what I can tell, Basic DeltaV is causing serious performance issues for me when I try to edit fairings. Editing gets very laggy the moment I start designing the fairing (only tested with the stock 1.25 Airstream protective shell so far). I can only guess it may have to do with a bunch of tiny changes to the mass, as the size of the fairing changes during editing.