Intel get drastically more instructions per clock cycle than anyone else, which is a very useful metric. Intel processors still dominate in single-threaded workflows. Meltdown makes that performance advantage look slightly suspect - Intel might be cutting corners to squeeze out extra IPC at the expense of security, reliability or accuracy.

Intel is cheating by validating the protection ring of speculative executions asynchronously, aka Meltdown, which makes this timing attack work in kernel space and requires the PTI mitigation. ARM does this on some cores too. AMD insists that they do not.