optimise lighting on tilemaps

Godot Version

4.5.1

Question

The lighting is a crucial part of my game, but recently I have been trying to optimise to get my game running at 60+ fps. It is occasionally at 60 but usually it drops to around 20 to 45 fps. Looking at the profiler Cull light 2ds seems to be taking ~6ms altogether render_viewports seems to take ~14ms
Cull Canvasitemtree also takes around ~6.07 ms
I have tried messing with the project settings but nothing has made much of a difference