I noticed that when i turn on frame generation, there is a noticeable lag spike when talking to or leaving a NPC dialogue window such as the blacksmith or occulitist or any of the similar NPC.
I see a slight hesitation once in a while when visiting/leaving a vendor, which would be similar, but I may experience it occasionally at a lesser degree with better hardware, if that makes sense.
But I run the Frame Gen all the time. In fact the game ran worse for me when they broke Frame Gen during the start of the current season. I had to completely disable RT while Frame Gen was unavailable to maintain 100+ FPS.