I have heard from someone who develops S/W for one of these firms that they are concerned about instruction timing and have uncovered situations where some inst

I have heard from someone who develops S/W for one of these firms that they are concerned about instruction timing and have uncovered situations where some instructions occasionally take longer to execute. They go back to the manufacturer to find out why. They remain a couple generations behind the latest processors until they can qualify the newer ones for all of these details. That's how far into the weeds they go.