Improving Performance with many Static Spotlights

I have an interior scene with about 200 Static Spotlights and 1 Static Skylight.
The performance isn’t terrible but need to optimize. I am also using ExponentialHeightFog for a volumetric effect.

I notice if I disable the DeferredLighting pass in cVars I get about a huge boost in performance. From around 50 to almost 90fps.

Similarly if I disable DynamicShadows I see about a 20% performance improvement.
Confused why this is the case since I am ONLY using Static lights and they are fully baked into the scene.

Can anyone offer suggestions as to what I might do?

Cost of static lights is not dependent on their number. Most probably, you are referring to stationary or dynamic.