Hi, this is Jan from Simulink Desktop Real-Time development.
The problem with 100% CPU utilization has no direct relation to the real-time kernel. It is because of misconfigured power scheme. Simulink Desktop Real-Time temporarily boosts CPU performance to 100% to ensure the fastest possible sample rate. Under normal circumstances, this gets restored back to the normal values when the real-time experiment finishes. However, if the real-time experiment ends abnormally (like MATLAB process killed from task manager or such), the power scheme does not get restored and remains set to maximum CPU performance.
For an immediate solution, the only advice I can give at the moment is to change to a different power scheme. That is, if your current power scheme is e.g. set to Balanced, set it to e.g. High Performance (or vice versa - just change it to something different). This should get the CPU utilization back to normal.
I understand that this is a temporary workaround and the issue should be fixed in some more robust way. And, there should be a way to fix the misconfigured power scheme without the need to switch to another one. I don't have a better solution right now, but the problem is being investigated and a better solution is on the way.
And, finally, a wish: please do report such issues via technical support. This ensures that development is notified and can respond in a much shorter time than I was able in this case.