It would have been sort of interesting if we’d gone down the road of often using interval arithmetic. Constant factor slower, but also the operations are independent. So if it was the conventional way of handling non-integer numbers, I guess we’d have hardware acceleration by now to do it in parallel “for free.”
You can probably get the parallelism for interval arithmetic today? Though it would probably require a bit of effort and not be completely free.
On the CPU you probably get implicit parallel execution with pipelines and re-ordering etc, and on the GPU you can set up something similar.