One of the best thing you could do is to isolate everything, or try to isolate and find out how the performance changes. Like the above advice try with “stat unit” as well, but if you are a beginner you should try things in a simplified mode.
I mean it’s difficult for a beginner to find out what’s wrong - in a complex level with all objects present, lighting and all effects.
But it’s easier if all or most objects are stopped, or hidden, and have only let’s say a textured cube present. Or the ground. Or let’s say we suspect the shadows are using too much power. What if you stopped the generation of shadows all together ? Does to FPS jump up ? Do they double ? Or maybe the FPS remain mostly the same ? That would indicate the problem lies elsewhere.
If you want 120 fps, in what conditions do you get that ? What do you need to stop to get 120 fps ? The lighting ? or part of the objects ? The textures ? Shading ?