[Bronz]

E-Ink devices have much slower refresh rates due to the way the screen works. So what you are seeing is the normal behavior of the device without specialized optimizations. The reason the annotations work faster on BOOX devices is because Onyx has a developer library that lets developers access something they call "Raw drawing mode" where it turns off the screen refresh and flips pixels when the stylus touches the screen, making it seem like writing is happening without any delay. I imagine Sony must internally use a similar approach if their own software doesn't have delays with writing. Unfortunately, I'm not aware of any library for the DPT-RP1 that I could utilize for that kind of functionality, so little can be done to improve the responsiveness. If you are seeing missing lines, that would imply that touch events are being lost in some manner, or aren't being reported quickly enough to MobileSheets in order for it to generate a smooth drawing. That's also an issue with the hardware or OS implementation.

Mike

EDIT:
Looking at this https://github.com/DPT-RP1/dpt-canvas, some users have found ways to get better performance on the DPT-RP1 but it requires a different implementation and handling of invalidation and touch events, so it's not something I can easily integrate.

Thank you, Mike, for your detailed explanation! So, as often, things are not as easy as they look at first glance...