impressive tip from robminer80 who gives better advices than the dev !
Probably thanks to the repartition on cores 1 and 3
I postpone 0.29d to make more tests and add coin BLOC (another CN-Heavy coin)
Apu's L2 cache is 2MB + 2MB in two modules, Cpu 0 and 1 have access to the first 2MB, Cpu 2 and 3 to the other 2MB