Yes that is understandable. But the performance of file based IO is very poor (as pointed out to me again by a customer today). Also I think the current latency through the IPC api also has a significant impact on IO performance.
Maybe the answer is for Sierra to supply a linkable library that hides the hardware implementation but has little impact on IO performance ?
I notice that there is an open issue in the release notes
Only one service is able to access a GPIO pin at a time
Perhaps when that issue is addressed the speed can be addressed as well?