Overhead should be minimal but something is preventing it from working as well as it theoretically should. AFAIK Microsoft has been improving VBS but I don't think it's completely fixed yet.
BF6 requiring VBS (or at least "VBS capable" systems) will probably force games to find a way to deal with VBS as much as they can, but for older titles it's not always a bad idea to turn off VBS to get a less stuttery experience.