I have made a chatbox which adds simple widgets as the chat messages to a vertical box, this however causes some serious performance drops while the chat messages exist, as they disappear the performance is restored, I lose about 20 - 30fps for each widget created, when more than around 10 - 12 appear the NVidia drivers crash.
This can be replicated by creating a vertical box, and a second widget with some text in, then in blueprint creating a button which adds new widgets to the vertical box. Once 5 - 15 widgets are added you will get a recoverable NVidia driver crash, or if you are using an AMD GPU you may encounter a bsod.