At slower speeds, enough that depending on what you're doing, it's not usable. And it's not guaranteed to work anyway. We had some processes which I guess were

At slower speeds, enough that depending on what you're doing, it's not usable. And it's not guaranteed to work anyway. We had some processes which I guess were compiled to use instructions that qemu wasn't emulating, so they would crash with illegal instruction errors. Another annoyance is that your package repo may not actually publish arm versions of packages you use. This is usually the case for older stuff, e.g. MySQL 5.x was not released for arm and won't compile without backports. So, to fix the performance issues with emulation you may need to build some things yourself. Not a big deal, but also not an out of the box experience.