Your linked drive doesn't seem to have any readme or documentation for how this is invoked. Please see:
https://www.qemu.org/contribute/report-a-bug/ Specifically the host/guest details and the full command line that you have used to run this binary. As developers may be wary about running on unknown binary on their systems you may find it quicker to do some experiments yourself. If you run qemu under perf for 2.12 and 3.0+ (or current git) that might give some indication about what has changed. ** Changed in: qemu Status: New => Incomplete -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1812694 Title: qemu-system-x86_64 version 3.0+ is 20 times slower than version 2.12 Status in QEMU: Incomplete Bug description: 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 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1812694/+subscriptions
