Hey thanks for the answer. I can confirm turning of specularity solves the performance hits but also I noticed that the spec switch also enables parallax mapping (which seem to be the real performance impact here). Is this an idtech4 thing, some confused setting or intention?
I don't know the idtech4 nor how advanced your OpenGL knowledge is or what is already done but I would suggest the following:
The parallax value could be decreased by distance till turning it off completely this will make surfaces which are further away not causing additional parallax calculations since you wont notices them anyway also I would limit the amounts of light sources which are causing spec lighting also by distance and also limit it to 8 sources at max and also limit those to light sources in front of the camera.
I don't know if the engine does this already or if this is an optional thing or can be enabled somehow but I think you'll know it :D
VortexAcherontic
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