qemu-system-x86_64 version 3.0+ is 20 times slower than version 2.12

version 3.0+ is 20 times slower than version 2.12
I wrote a small 64-bit operating system (SIGMAOS) in which I use the lzma decoder. unpacking the file takes 20 times slower than in version 2.12.
You can download it from https://drive.google.com/drive/folders/0B_wEiYjzVkC0ZGtkbENENzF1Nms