Multithreaded Lightmap and shadowmap encoding

Dear Epic,

I just saw these 2 options “Multithreaded Lightmap and shadowmap encoding” under editor experimental features. There hasn’t been any mention of these features yet, except for the docs once.
Can someone explain what the drawbacks as of now are? Does it crash, does not not work with scenes/textures larger than X?

Thank you very much in advance.