When, on Mac, it starts to go slow, either you have bad memory stick, either you starts to use VM because you have a lack of physical memory !
I don't know about Windows, this could be something to check
Is the Bosendorfer patch much bigger than the C7 patch ?
Can you look at memory occupation ?
MacBook Pro M3 MAX 128 GB 8TB - 2 x 48" screen --- Logic Pro --- Mir Pro 3D --- Most of the VI libs, a few Synch... libs --- Quite a few Kontakt libs --- CS80 fanatic