what is this "raytracing dynamic geometry update"? (sorry , i'm a noob)

its been 4 days that i am trying to find out what this “raytracing dynamic geometry update” is and why its taking more than 14ms to be done . . .

would you plz tell me how i can get raid of it ?

i just deleted my landscape and things are normal now . i made a landscape using this method and now my framerate is 30fps .i looked for “stat gpu” on cmd prompt of ue4 and i found this. i am getting 14ms for raytracing dynamic geometry update . this is the method .

another post related to this topic which was posted 2 years ago .
https://forums.unrealengine.com/development-discussion/rendering/1779938-raytracing-landscape-become-very-slow-when-camera-moves

i am writing this now even though its already too late . there is a process called bvh testing that is related to raytracing dynamic lights . my game has a day and night cycle which requires the sky light and the directional light to be movable which means its dynamic . the engine needs to process the dynamic shadows for every single each frames instead of baking the static ones for once in the beginning of lunching the game engine . My chances were :

  1. Delete your day/night blueprint and run an openworld game only on daytime