If your kernels are not too long, there will be a normal user experience. Below about 25fps you will start seeing degradation (games may require a bit more). So if your kernels run for longer than 40ms you will start seeing degradation in performance.
I don’t have experience with that kind of workload but you can’t give 100% GPU to both CAD and FEM, so if they both try to run at 100% at the same time, you’ll see degradation. The performance won’t be very poor, it’s a powerful card and with two applications, even if they try to run full force at the same time you still get 50% each. 2d applications will mainly be affected by the frame rate, so you need to make sure that you’re kernels are below about 40ms per run.