Developer Tool question

Hi guys, I’m wondering if someone can help…
I’ve had the in game developer tool on since launch day and after many hours fiddling with settings I’m pretty happy with the results. Yesterday I was getting 60 plus frames down to low 50’s and the developer tool was always in green but limited by GPU. Today however when it drops below 60fps it turns red but there’s no noticeable drop in performance and still says limited by GPU. Odd. Does anyone know why its turned red? Could it be because I’ve cranked the level of detail slider and object slider right up?
8700k @ 4.9, overclocked 1080Ti, 32gb.
Thanks guys…