Yes, this is so true. When someone has a true jitter-sensitive task that needs to run on say microsecond or sub-microsecond accuracy, that is not for the realm of a high-performance CPU with caches even if it is on a RTOS. My first question is if that tight of a bound is truly necessary or just an over-specified requirement. If it is necessary, I say do that in hardware or on a simple microcontroller (e.g., Cortex-R) if that is truly your requirement.