I have Project Nevada, Rudy ENB, NMC Texture pack, and Realistic Wasteland Lighting installed.

I'm having this problem where when I change my vision modes, the game freezes for about 3-4 seconds before actually switching to it.

Is there anyway to get rid of this?

Thats a whole lot of textures to re-render and exacerbated by your texture and lighting mods ... a pause is not suprising.

I'd say a better GPU would fix it or lowering the quality. But maybe some tweaks in the advanced settings