Hello, This is actually my first time attempting to play Unreal so bear with me a little please. I've been trying to turn off Dynamic lighting, mainly because my PC has some FPS drop only when I'm facing toward any light source, however whenever I uncheck the box it simply turns itself back on whenever I close out of the options window. Is there a reason for this, or could this even be simply fixed with a mod? any help would be greatly appreciated, thanks.

Are you using Direct3D or Glide, or have you installed the Oldunreal 227i patch? The vanilla version uses DirectX 7 for Direct3D, which isn’t particularly smooth, especially since modern computers aren’t optimized for it. The GOG release actually is preconfigured with nGlide, which converts the Glide calls to the DirectX 9, which is better optimized. The 227i patch adds native DirectX 9 and OpenGL 2.0, which might be able to better run the Dynamic Lighting on your computer or even help turning it off. There also are DirectX 10 and 11 renderers available elsewhere.

TL;DR: What renderers have you tried?