01
Performance
Frame timing, memory pressure, allocation, and profiling methods for responsive interfaces.
02
Graphics
Drawing, compositing, shaders, images, animation, and the Android rendering pipeline.
03
Layout
Measurement, hierarchy, reusable structures, scrolling, and invalidation boundaries.
Working rule
Make the next measurement cheaper than the next argument.
Keep a minimal reproduction close to the observation. Change one variable at a time, preserve the failing path, and prefer before-and-after evidence over a broad rewrite.