When using the fullbright feature from visible barriers, the fullbright takes a few seconds to activate. This started happening, when I upgraded from version 1.4 to version 1.6 of this mod. A fix would be appreciated.

Does the fullbright from boosted brightness also have this issue?

I don't know, Tweakeroo Gamma Override works fine though.

I don't know, Tweakeroo Gamma Override works fine though.

Yes, the lightmap optimizations check for gamma. Unfortunately, checking for other types of fullbright from this mod aren't possible without a lot of over complications, but why aren't you using gamma fullbright anyway?