Thanks. That makes sense. I think I should have phrased that question (#3) differently, since there's a huge difference between relative and absolute speed & performance.
What I had read as implied in the SO answer I linked to was that there was some other means of implementing cross-architecture emulation that was faster than QEMU.
In other words, there's a difference between being "slow" in absolute terms vs. being "slow" relative to other virtualization solutions.
From your answer, I gather that QEMU isn't under-performant relative to other emulation options.
What I had read as implied in the SO answer I linked to was that there was some other means of implementing cross-architecture emulation that was faster than QEMU.
In other words, there's a difference between being "slow" in absolute terms vs. being "slow" relative to other virtualization solutions.
From your answer, I gather that QEMU isn't under-performant relative to other emulation options.