I have a similar problem with my Volla Quintus, see : https://forums.ubports.com/topic/11263/frame-rate-and-slow-animations-movies .
I am already in contact with Volla about this. But because "laggyness" or "low framerate" is quite subjective (not easy to measure in technical terms), except you can record the screen in high framerate and without aliasing, it is not easy to talk about and to discuss this problem.