Yes, already noticed that, and these last builds the browser was closed and the Unreal editor minimized…so there was nothing going on in my computer appart from the build light…the funny thing is that the ventilator of the GPU is almost not working when baking that level, wich means the calculation goes slower as normal during those bake lights…but if I bake anything other, like the same level with just a part of the whole project, the ventilator is working full and the velocity of bake is back to normal, also in the build statics when it goes slower it says “overall xxx seconds 10.72Mrays/s” and in other cases can go up to 277,76 or 340,22 Mrays/s, so I guess that is something more objective than the ventilator 
…not sure why all this happen
EDIT: after 7hours of waiting, only got 10% done at an “overall 22332.44s 16.33Mrays/s” and still 47h to go, but it looks like the most it does the slower it gets… the GPU is almost not working, resource monitor says it is at 5% (CUDA 0-100%)…the Memory at 60% and the CPU at 21%
It looks like performance is down and I do not know why…ANY HELP?