[Zubersoft]

I do my testing on a Samsung Tab S4 which has a resolution of 2560x1600, so it's not that different from the Pixel Slate. I experience no slowdown at all while annotating as far as I can tell. So this leads me to believe the problem may have something to do with ChromeOS. I have a Samsung Chromebook Plus I can perform some tests on, but the specs are not nearly as good as the Pixel Slate. If you can capture a video showing the slowdown, this would help me to understand how significant the problem is compared to other apps on your device. I just want to be able to quantify the slowdown (i.e. 20% slower vs 50% slower) to see if perhaps some smaller optimizations could be made to help with this versus requiring a completely different rendering model entirely. Right now, every time you draw something, all annotations on the screen are constantly redrawn in Android's rendering framework as they are all owned by the same parent view (the page behind is not redrawn though, reducing the required rendering load). If you get the slowdown even when annotating a page with no previous annotations on it while drawing a circle in freeform mode, let's say, then that would indicate that the way I'm rendering the freeform annotation is an issue.  If the slowdown only occurs on pages where you already have a large number of annotations, then that points to a problem with how much is having to be redrawn over and over. In that case, I could look into an optimization where the only thing being rendered while the stylus or finger is down is the current drawing, which would be drawn into a separate layer. Once the drawing is complete, I would commit it to the same layer as the other annotations. 

The more information you can provide, the better. Without being able to see the problem myself, it will be hard to know what to change. I'll set up my Chromebook here in a bit and run through some tests on that at least.

Thanks,
Mike