Lights evaluation is what takes the most time in eevee. Using Clustered light culling, we could cut down the evaluation time by evaluating only lights present in the view.
This needs further investigation as how to communicate what lights are visible. Light Bits is the most straight forward way but it severly limits the number of lights per froxel.
Also findMSB (glsl bitscan) is GL 4.0 only, so need to review other alternative. (avalanche studio slides link).
We need a way to cull thoses on GPU (pixel shader per froxel?) for efficiency.
Need more investigation about the state of the art techniques.
Issue is that it takes another texture slot. Could we use a UBO instead and use bigger froxel? (Can't write to UBO using shaders)
Estimate : 2 weeks