Developers will be able to take advantage of new Apple Pencil latency upgrades announced at WWDC19 (via Macrumors).
During WWDC19 Craig Federighi announced that in iPadOS, they were able to cut the latency of the Apple Pencil from 20ms down to 9ms.
Developers will be able to receive the “latest and greatest” improvements as noted in an email from Mr. Federighi:
Note that we achieve low latency through a combination of several techniques: Metal rendering optimizations, touch prediction, and mid-frame event processing. Third-party developers can achieve similar low-latency drawing experiences by taking advantage of Metal rendering and touch prediction best practices covered in the WWDC Sessions I’ve referenced below.
With these you can achieve nearly all of the improvements you’ve seen in PencilKit drawing with your own renderer. (There does remain a small gap: 4 ms of our improvement comes from a technique called mid-frame event processing; we are looking for ways to expose this capability to third party engines in the future, but for this year this one was only safely achievable through tight integration within our frameworks).