[wahern]

> Predicted branches, like that while loop, aren't that expensive.

The dispatch loop conditional used to be quite expensive. Since Haswell it has become much less expensive, such that it wasn't even worth threading dispatch. But now with Spectre mitigations that cost may rise again.

Also, it depends on how tight the VM loop is. The prediction buffers are only so big, so if your ops are doing alot of work you can end up back with pre-Haswell performance.