Investigation showed that Weston rely on GPU for composition, neglecting any other hardware acceleration present. Hardware platform provided support for composition acceleration (overlays). Weston lacked logic of hardware acceleration and it's synchronization framework was inadequate.
Hardware acceleration awareness was added with ability to enumerate overlays. Synchronization framework was refactored into atomic modesetting model, able to synchronize on all overlays available to prevent artifacts. Usage of hardware acceleration as a first priority was added, GPU composition was set up as a fallback. Performance on use cases which used less then certain treshold number of layers raised significantly(from ~10 fps to ~60 fps)