Custom Slate widgets that draw their own shapes can cost game thread time on every frame, even when nothing on screen changes. This tutorial explains what tessellated geometry is, how Slate renders it, how to profile the cost with stat unit, stat slate and Unreal Insights, and how a record-and-replay cache cut the cost of 16 charts from 1.0 ms to 0.4 ms per frame on Unreal Engine 5.8.
https://dev.epicgames.com/community/learning/tutorials/KJEPe/unreal-engine-caching-tessellated-geometry-in-slate-ue-5-8